I'm experienced at Photoshop (CS2), but new to GIMP. What tutorials, FAQs, and tips can you recommend to make the transition simpler?
EDIT: Giving up on GIMP. Going back to Photoshop.
Link: Official GIMP Doc.
Link: Handy Tweaks To Make GIMP Replace Photoshop covers a couple features Photoshop has by default, but need to be manually enabled on GIMP.
Tutorial: How to make GIMP have Photoshop's Layout
Tip: Click Edit -> Keyboard Shortcuts, and read down the list. It's a great summary each all GIMP's functions, what keyboard shortcut invokes them, and where they're located in the menus.
Tip: Don't expect any of the keyboard shortcuts to be the same! CTRL+D is now Duplicate, not Deselect. Transform Selection is now SHIFT+T, not CTRL+T, M is now Move, not V...
Tip: The default layer has no "Alpha Chanel", so deleting content (via the eraser, or DEL) erases it to the background colour, not transparent.
Tip: The default transformation interpolation in GIMP is "Cubic", whereas in Photoshop it is "None". You might notice when scaling solid colours and wondering why it fades out...
Tip: Space Bar MOVES now, instead of PAN. So you're no longer moving your view around the image, you're now moving the image around under your view... (At this point I'm considering VM'ing windows...)
Tip: When drawing a line with the pencil tool, if you want it to go straight (horz/vert/diag) in Photoshop you would hold SHIFT before beginning to draw. In GIMP, click once where you want to begin, then hold shift + ctrl, then click where you want to end.
Gimpusers.com has tutorials and videos explaining how to perform various tasks. There's also a forum, and regular notifications about updates to GIMP.
You may be interested in GIMPshop, it's GIMP but with a modified "Photoshop clone" GUI. However it looks like it has been abandoned as it has not been updated for years so learning the original GIMP is probably a good idea if that's what you will be using. Still, there it is.
In case you're using Windows, I'd recommend the Paint.Net application.
It might feel way more like Photoshop than GIMP, believe me!