Fantasy
I would love some elaboration on that. What's so cool that GIMP can do that Photoshop can't or does worse?
My obscure soft would be...
MP3Tag - monstrously good to bulk edit mp3 file names and tags. Especially good for me since my whole music collection is strictly mp3 files.
Hard Disk Sentinel - it is very useful to be able to catch the moment your HDD starts to go down and replace it in time.
FastStone Capture - hardly anything can grab a screenshot better and faster, in my opinion.
JitBit MacroRecorder - fast and simple macro recorder, allows you to record some fast macros for tedious tasks. Like, do a Brightness/Contrast adjustment on a hundred images and save them. I mean, you can't write a script for everything. Also, you can go really deep with JitBit and write some real deal macros with it as well if you feel like it.
MediaHuman Audio Converter - best audio converter I've seen at the moment.
MP3 Folder Structure Maker - name says it all. Once again, real good for my mp3 collection.
That's about it for obscure without going into really specific issues. I think I've named too much mp3-related ones as is.