If these gatherings are a regular enough occurrence, you should consider clubbing together and buying a cheap original X-Box (or PS2) and get games like Timesplitters 2, Timesplitters Future Perfect, Def Jam: Fight For New York, Mashed, Urban Reign... all of which are excellent split-screen games.
Split-screen gaming was much better last generation when there wasn't so much disparity between the capability of the consoles and how demanding the games were. Nowadays most games are too demanding to be rendered more than once on a single console, so split-screen is, in most cases, a technical impossibility.