We have quite a collection and still buy occasionally. We do belong to Blockbuster Online ($17.99 / month), and we can have 3 movies out at one time. If you drop them off at the store instead of mailing them back, you can get a free rental from the store for every return. The best thing about the online service is that the selection is enormous (much more than a store). If you like old movies, that's the way to go.
And anyone who knows... please tell me (us) that our old DVD's still work in the new BlueRay players. As I understand it, my XBox games would still work in the XBox 360's... I sure would hope that these new-fangled BR players would be backwards compatible with the 'old' DVD's.