A headset is worth getting to be honest. You can get a decent one for about £10-£15 ($20). It comes with a charger, and it wirelessly (via bluetooth) connects to your PS3. You can hear people talk, and talk back to them. Also stops random people shouting through the t.v or speakers if you are playing online (Although you can mute them anyway).
There are more expensive headsets you can get that plays everything (game sound as well as voices from other players) but you can at least double your cost of the headset then (probably triple) but not worth it, unless you are happy to fork that money out. Definately go with a cheapish headset though, as they seem to be fairly reliable and add a lot to your gaming experience online.
Ratchet and clank is online at the moment as a free download as well as another game as part of 'refunding' players for the playstation network being down. If you know any they might be able to grab that for free for you, or I'm not sure if you get a PS3 now if you can still capitalise on the offer.
Nothing else I can think of off the top of my head accessories wise.