Commissar Sae said:
Mount and blade warband is a lot of fun if you give it a chance. mind you its 30$ rather than 20, but theres a demo. Fire and Sword is 15$, but its harder to get into.
And don't forget that vanilla Mount & Blade is $20, and there are still a few mods for it that haven't been ported over just yet (Oddly I'm playing it more than Warband at the moment, without mods to boot.)
OT: Soo, 20 bucks for a time killer 'till L.A. Noire? Well, here's two suggestions: Log thine arse onto GOG and purchase thee something nice & cheap (Cannon Fodder!), or, if you're really looking at Steam, log on and look up X-Com. Individual games are 5 bucks a pop, or the collection is 15 bucks. That may sound like a deal, but personally I'd just skip Interceptor & Enforcer to save the 2 cent difference(Even there just pick up UFO Defense, that'll last you a while.)