For Christmas, my parents bought me a Velocity Cruz R102, which runs an old version of Android, and tends to be rather slow at most tasks. My brother received one as well, and we set to beefing them up.
One of the most helpful resources was this thread on slatedroid.com, which lists several ROM’s to download. My favorite has been this one, which helps to root the device, as well as overclock the CPU from 533 MHz to 800 MHz with SetCPU. It runs fairly well now.
Really, the best uses for this device is for reading PDF’s (I use Repligo) and running light apps. It will run some games, but don’t expect to play Angry Birds on here.