GSpell is a great little add-on for the Mac OS that basically uses the power of Google as a spell-checker for all your desktop applications. It works in Word, Firefox, email.... everything on your computer. It's cool because it searches the internet for the misspelled word, so it automatically knows words that your computer's dictionary wouldn't know. For example:
Spell checking phrases in TextEdit. Direct download to .mov file if above clickiness doesn't work.

Teachers and students alike come to me on those horrible days when their files have suddenly and inexplicably disappeared without a trace. Here is a great article about recovering your data when it goes missing....

How to Recover Deleted Files with Free Software

Ack! The computer ate my term paper! We've all been there at
some point. You delete an important file, somehow it skips your Recycle
Bin altogether, and for all practical purposes, it's disappeared into
the ether. But before you hit the big red panic button, there's a very
good chance that your file is still alive and kicking somewhere on your
hard driveyou just need to know how to find it. With the right
tools, finding and recovering that deleted file can be as simple as a
few clicks of your mouse.

Part I: The Overview

Ok, so you've lost an important file. Don't panic. Take a breath, and let's see if we can find it. Before you go into full-on file recovery mode, make sure you double-check the folder you had saved it in and the Recycle Bin or Trash. Still nothing?

1. Stop What You're Doing

When your operating system deletes a file, all it really does is mark
the space on your hard drive that your file occupies as free space.
It's still there, but your computer is now perfectly happy to write new
data on top of itat which point the file recovery process
becomes a lot more difficult. That means you should do as little
computing as possible until you find the file you're looking for, since
every time you save a new fileevery time your computer writes
information to your hard driveyour chances of recovering the
file go down.

2. Find the Right File Recovery Program

Windows: You've a lot of really great freeware options for file recovery if you're running Windows. Notable apps include Undelete Plus (original post), PC Inspector File Recovery (original post), and Restoration (original post).
Undelete Plus is the most user-friendly option of the bunch, with
advanced filtering options that make it easy to find your needle of a
file among the haystack of deleted garbage, but in my tests I found
both Restoration and PC Inspector File Recovery to be more effective at
recovering files. (Of course, your mileage may vary.) As an added
bonus, the bare bones Restoration is portable, which makes it an
excellent addition to your thumb drive.

UPDATE: Per several readers advice, you may also want to check out Recuva (original post), another freeware Windows file recovery tool.

Mac: If you're on a Mac and aren't afraid to lay down a few bucks in the name of data recovery, the $99 Data Rescue II is the go-to application for file recovery with a friendly graphical interface.

All Platforms: If you're not afraid to crack open a terminal window or command prompt, the free, cross-platform command-line tool PhotoRec (original post)
is a crack shot at recovering photos (as the name implies) as well as
virtually any other file type from your removable media or hard drives.

3. Recover Your Files

Once
you've picked a tool, it's time to scan your hard drive for your lost
file or files. This process varies depending on the app you're using,
but it's basically the same for all of them: Just point the program at
the hard drive or folder that was holding your missing file and start
your scan. Once the scan is complete, you're going to see a big list of
jumbled file names. Often most of these files are nothing more than
system files that your operating system has created in the course of
basic operation, and you won't need to worry about them. You're just
looking for the file type and name that matches what you've lost.

Once you find what you're looking for, saving it is a matter of right-clicking the file and choosing where to save it.

Went through steps one through three and still aren't having any
luck? It might be worth trying again with a different application,
since there can be a lot of variation between apps. If you're still not
having any luck, part two discusses a few other ways you can try
addressing more specific problems when your data goes missing.

Part 2: More Specific Problems

Above you got a basic overview for recovering deleted files from your
computer. Now we'll take a closer look at some more specific problems,
methods of data recovery, and tools that may be of help in your quest
for your elusive lost data.

Recover Files from a Wiped or Unbootable Hard Drive

So
you didn't just accidentally delete a file or two and empty your
Recycle Bin prematurelyinstead you've got a whole hard drive
worth of missing data. You can still use many of the applications
mentioned above to recover files from these drives as long as you have
or can get the hard drive into a bootable computer. For more details,
check out how to recover files from a wiped hard drive with PhotoRec (original post) or how to recover data from a crashed hard drive with PC Inspector File Recovery (original post).

If you can't or don't know how to get your unbootable drive into another computer, a Linux live CD can be perfect for rescuing files. If the Linux route scares you off, give the popular BartPE (original post) a try.

Finally, if none of these options can even read your hard drive, you
still might be able to get it working for just long enough with a few
tricks of the data recovery trade, like putting the busted hard drive in the freezer.

Recover Lost Photos

If
you need to resurrect photos from a damaged flash memory card from your
digital camera, you'll be happy to know that most of the applications
listed in part one above will do the trickyou just need plug in
your camera or insert the card into your computer's card reader before
running your data recovery application of choice. That said, you can
find other applications, like Zero Assumption Digital Image Recovery (original post), that are focused specifically on image recovery that you may want to add to your data recovery toolbox.

Recover Lost Word Documents

If your lost dissertation was saved as a Word document, you've got a
few more interesting options for getting to your lost or deleted
documentsread more about them here and here.

Recover Data from Scratched or Corrupted CDs and DVDs

If
your munged data is sitting on optical media like a CD or DVD, the
recovery process can be slightly different. Freeware application CD Recovery Toolbox (original post)
is made specifically to read the portions of a CD that are readable in
an effort to rescue as much data as possible from a damaged disc. If
that doesn't work, you may want to give a look at the 30-day trial of
shareware application CDCheck, as recommended by a reader. Then again, if scratches are the issue, you may be able to get away with simply fixing your scratched CD or DVD yourself.

Part 3: Don't Let This Happen Again

Whatever
the cause of your lost file, the best method of data recovery is a good
preemptive data backup plan. If you're on Windows, we've taken you
step-by-step through how to automatically back up your hard drive
so that this sort of thing never happens again. If you're running a
Mac, do yourself a favor: Get an external hard drive and flip the
switch on the easy-to-use Time Machine. Linux users should check out backup options like FlyBack, TimeVault, or the time-honored rsync.

Have you ever raised deleted files from the hard drive graveyard?
What software did you use to do it? Tell us your tales of file recovery
victory and woe in the comments.