It would be possible, but the performance gains would be next to nothing. You'd be better off buying a single high quality SSD than putting two in RAID. It might be cheaper and you won't notice the difference in performance If you wanted to get higher capacity, then it's probably better to just get a higher capacity SSD
One more question.. a friend of mine told me that I could run an SSD as my main drive and play games off of my HDD with the performance benefits of the SSD carrying over. Sounds pretty farfetched to me, is there any truth behind it?
SSD shouldn't have any impact on your games, except for load time. If you installed your games to the SSD they might load faster, but there won't be much difference. The only basis I can see for that statement is having your swap file on the SSD might increase speed slightly.