“You can run OSX on it.”
I wouldn’t run anything higher than 10.3 (Panther) on that machine because of the memory limitations...I think the G3 iMacs max out at 512 mb. You can get Panther install CD’s cheap on Ebay as well.
Yeah. It depends on what you want to do with the machine. For simple web browsing, word processing and such, one of those with 512 is okay and somewhat enjoyable.