Yea i usually dig them out of temporary internet files folder on desktop xp machine and copy them over to nokia.

I've got a zip file with several flash games and clocks which work fairly good up at :
http://wardenclyffetower.com/MaemoFiles/flashfiles.zip

They run a bit slow so you might have to experiment with windowed mode, fullscreen mode, or even zooming. You can also try right clicking flash to choose low quality mode, or in the pharoes tomb game use menu to disable animations and set to low quality. These games also benefit from 2008 speed bump to 400mhz. The acid factory game bogs down with dpad button but if thats kinda a device driver thing so i left it in there... 810 users might find very usable mapping to other keys on keyboard.

Flash games do have drawback that they dont really have save game feature so you either have to restart from beginning or remember some long/weird level code.