This one is a little bit of inside (blogging) baseball, but I know a lot of our readers blog themselves and so might find this tip handy. Ankur Kothari (whose Quicksilver customizations we've mentioned before) has cooked up an excellent little Quicksilver plugin called IconGrabber that does exactly what it sounds like. It allows you to easily create an image of an application icon at an arbitrary resolution in one of several popular image formats. Using a few simple terminal commands to change the defaults you can select the default image size and format. So, for instance, here at TUAW we post lots of icons at 125px wide in the jpeg format. With IconGrabber I can now create those images in one step as you see above, where I'm saving the Time Machine icon to my TUAW pictures folder. If you're not a Quicksilver fiend, Ankur also has a stand-alone application to do the same thing. In any case, if you regularly need to extract icons as images, IconGrabber is a godsend.
IconGrabber is a free download for either the Quicksilver plugin or the stand-alone application. The instructions for customizing are in the announcement post and the comments below.