I have never rented a game since I first got my PS2. I have nothing against doing so, it's just I have never really been let down by a game I have bought (R:FOM is a different story) so I usually trust my choice of games and just outright buy them.
I was thinking about getting a membership for the local Blockbuster tonight but I have no money so I wouldn't be able to buy a game even if I really liked it.
I think I might start renting games once I get some cash, Blockbuster is a 5 minute walk from my college so I can pick up a new rent during my dinner hour. LoveFilm (English NetFlix) is a good place to rent games online but I would rather pick the game off a shelf although I do like the list you can make just in case you forget what you want.
My first rents when I get the cash will be R6V2 (not convinced it's worth a buy), MX vs ATV Untamed and Brothers in Arms Hell's Highway.