A lot of good stuff listed in this thread.

Since I tend to read the forums at AtariAge on my N810 quite a bit, I have ported the lastest Atari800 emulator to n810 and haxored it up so that you can make every keypress (N810 keyboard + xkbd). I've also avoided the keys that are being used by Telescope... a big problem for me with the previous version of Atari800 that was ported to N8x0. This isn't in the repos, but it's in my garage page.

https://garage.maemo.org/projects/atari800/

You can use it to play some games, but the N810 is just a bit too slow to emulate the system at 100% without doing some frame-skipping... I use it mainly to quickly test things out that people post in the forums.

I've also ported Handy_SDL to N810 (Atari Lynx emulator), but there is a proper port for the N900 that is much better... hopefully someone will backport that to the N8x0. Games are playable without sound... and it's CLI only. No garage page for this one yet...

I also ported Haxima/Nazghul... but there is a bug that causes it to crash fairly early on in the quests... haven't figured that one out yet.

https://garage.maemo.org/projects/nazghul071/

I've noticed that there's not much being developed for the N810 in this community anymore... most activity is on the N900. It's too bad more stuff isn't being backported, but I guess the lack of hardware 3D really hurts. I've been thinking about buying a N900 to get more "up to date" (LOL).