Just earlier today someone emailed me asking if there was some way to create gestures in xGestures that would take screen shots, like pressing command-shift-3. I figured it would be a pretty simple thing, since you can create keystroke actions and just have one of those press command-shift-3. What I found out is that even if you get passed the first hurdle of figuring out how to enter that keystroke the xGestures preference pane without actually taking a screenshot instead, it still doesn't work. There's a bug in xGestures I'm going to try to address as soon as I get the chance to make those sorts of keystrokes work, because apparently any kind of system-level key command can't be triggered by xGestures.
Not to be defeated, though, I figured that maybe there was some kind of neat way to do it using AppleScript. And sure enough, there is. Hidden in Mac OS X is the unix command screencapture, which can be used to take screenshots in exactly the same way as pressing Command-Shift-3. Unfortunately it requires you to give it a path to a file, rather than defaulting to saving the screenshot to the desktop in the form of 'Picture N', so I had to code something in there to make it do that on its own. But here are three AppleScripts you can use with xGestures (or anything that can run AppleScripts, like Quicksilver) for taking screenshots:
This will take a screenshot normally, just like pressing Command-Shift-3:
repeat with i from 1 to 999
set pathToTest to ("~/Desktop/Picture\\ " & i & ".png")
do shell script ("/bin/ls " & pathToTest)
do shell script "screencapture " & pathToTest
To make it behave like pressing command-shift-4, replace the last line with:
do shell script "screencapture -i " & pathToTest
or to make it behave like pressing command-shift-4-space, replace the last line with:
do shell script "screencapture -iW " & pathToTest
Hopefully someone might find these useful. There's some other AppleScripts I wrote in response to user questions for xGestures, and at some point in the future I'll probably post them, since other people might like to have them too.