I've got two. A new iMac 20" 2.0GHz, currently with 1GB RAM but soon to have 3GB once the chip I've ordered arrives, and a PowerBook G4 12" 867MHz with 640MB RAM. I use them both for business stuff (the 20" screen is just amazing for seeing my accounts spreadsheet all at once 🙂), for remote controlling client devices, and in the case of the iMac for all sorts of media stuff (mostly iMovie and Garageband). I'm going to be buying a copy of VMWare once I've got the extra RAM installed, which will have virtual Linux and Windows machines running inside it for investigation purposes. The PowerBook already dual boots Linux and OSX and carries round a whole bunch of security software.