Sam n Max Talkie is working great for me on beta2.
I managed to get the complete talkie version down to 65.8MB!! Happy happy joy joy!
On my 512MB stick I have a Genesis emu with roms, SNES emu with roms, Dead To Rights, Rengoku, Puzzle Bobble...I love it!
On that note, I'd like to recommend http://quick.mixnmojo.com/software.php Download that for ease of compression, and get the latest daily build from scummvm.org. Place SCUMMVMQ+E in the same folder as the latest build and run the program.
Click the system icon (top left) and choose "additional tools". You'll be prompted to download some missing files, so just click "ok". From there it's an easy GUI to compress your games down to a memory-stick friendly size.
That GUI only applies for .SOU-files. I'm currently working on compressing Full Throttle and it's a bit of a job since the tools don't support batch encoding yet, but I'm getting there. I have Full Throttle working now after I compressed the .SOU-file from it, but I haven't yet started compressing the included .SAN files. I'm sure I can get it down a lot in size, but still have it playable.
I have also compressed the entire Curse of Monkey Island, but it seems that this has some problems playing on the PSP. I blame it on the 640x480 display setting. This means it runs, but I get a display that's divided into four rectangles, each showing the top-left of the actual display. I may be asking for a lot here, but is it possible to implement a downsize-function for this game? It's also running a bit slow from what little I can gather by looking at the display in it's current state, but it's not so slow as to be unplayable.
Anyway, I think I have the hang of it now, so if anyone want help with compressing files to fit better on a memstick, post in this thread and I'll answer as best I can.