What can I say? This is my third mac, but its the first thats been around long enough (and was capable enough) for me to tinker with. Since I bought it last year, I've added another 128mb ram (totaling 256), a small storage drive from a performa 550, and a 4x SCSI CD RW. Future plans may involve a CPU upgrade, adding an ATA, USB, and possibly a firewire controller. Its main drive at the moment is a 2gb scsi, but once I get the ATA controller in I will upgrade it to something larger.
Its current specs are as follows:
200mhz PPC (604)
4x/16x external SCSI CD-R (no RW support)
Everything else is pretty much in it is original.
These machines offer great expandability, and you can usually pick one up nowdays for $50-100, depending on configuration.