The EmuTOS community is also wonderful - a couple years ago I was writing a small driver and the folks on the mailing list gave me a lot of encouragement and guidance until my driver finally ended up in the official tree (and now EmuTOS natively supports the UltraSatan RTC)

Also, let's not forget about some other amazing projects at even higher levels of the OS stack: FreeMiNT and XaAES

Multitasking with a real Bash shell on a 4MB ST is a reality (and kinda mindblowing) - not to mention what you can do if you get some more RAM and have Ethernet/USB also working :D