'm not sure if it has to be console games and online, but I came up with a solution 6 years ago that took away all the pain when hosting some beer-gaming-gettogethers.
I have a gamecube and a PS2 and the controllers kept failing or breaking from severe use, and therefore I upgraded my computer to be quite strong.
I bought a couple of controllers for my PC (Logitech ChillStream (great controllers)) and since then I've had no issues entertaining the guys when we were bored, or jsut in the mood to get wasted.
Wether it's legal or not, it's up to you to decide, but since I already owned the games I found it alright.
Get a gamecube emulator (Dolphin), Nintendo 64 emulator (Project64) and the newest party games released, then you have the newest games and the old favourites, like
Mario Party 1-7 (Virtual Board game with mini games, clear winner)
Smash Bros (Platform melee fighting game)
Mario Kart (Good ol' racing both "64" and double dash)
Super Mario Strikers (Soccer game 4player, with magic and "super strikes")
Dungeon Defenders (like mentioned in the thread, tower defense)
Blur (Racing game lige mario kart, jsut more "racing"-like)
Street Fighter X Tekken (new and more native controls instead of advanced combos, and special moves)
All of the above mentioned games are compatible with 4 USB controllers on win 7, and runs with "true" 3d graphics even the old N64 games. The mario games does have a cartoonish look, which makes it even more fun, cause you don't take it too serious.
Of course alchohol upps the fun.
The controllers with an extension USB cable and an AC powered USB-hub cost me around 180 euros 6 years ago, and they're still intact. Furthermore the stronger computers get the more consoles you get to emulate with smooth performance, so it surely has been a great investment for me.
Hope this can help
-PlayassDK