Remember
BeOS, the super-nifty object-oriented operating system of the 1990s? Well, BeOS itself may be no more (apparently Palm bought it and then proceeded to not do much with it), but there is now
an open-source BeOS-influenced OS named Haiku, which appears reasonably functional. There are images downloadable which you can play with in VMWare Player or similar. There's an article about it
here.