One of the hottest things in the industry right now are Solid State Disks, unfortunately they are so freaky expensive that unless you are rich, you likely can't afford them. What if you do not need a Formula 1 Speed rated SSD and can compromise on performance a little ?
Guru3D picks up a couple of cheap CF cards, and IDE-CF converter and a CF RAID controller to see where the experience ends. For roughly 50 to 75 Bucks you can build a pretty interesting CF RAID array.