Hi CritAnime - I'm doing a similar thing with one of my A600s. I've got a nicely retr0brited affair that has a 4Gb CF just waiting to go in.
As well as the totally necessary WHDLoad (which will be registered) I intend on adding the following:
Final Writer <- Good for most WP stuff
Octamed <- Possibly v4 as Pro might be too much
Protracker <- For the bits I can't do in Octamed
Imagine <- I've got v4, but may wait for an ACA630
DPaint <- I've still got V3 and love it!
Blitz Basic <- And why not?
Videoscape 3D <- It was regarded as a joke, but I love it
C Compiler <- Not sure which one yet
SDL Lib <- For the C compiler (natch)
As for other system-type things, I'll most likely add:
Anim <- Yeah, I know. But it's great with VS3D!
The rest will be a voyage of discovery and whatever mood I'm in. If I'm not careful it'll overtake my A1200T-040/25-160PPC as my main Miggy...
Ooh - remember piccies, though