Despite what your teenage neighbors tell you, you're not too old for a powerhour -- but you're definitely too old to spend an afternoon laboriously compiling a soundtrack. Instead, download iPowerHour.com.
iPH is a free program that automatically sequences any iTunes playlist into a rapid-fire powerhour mix. Just launch both programs, select your playlist and click PLAY on the iPH window. It'll then snap through a song every minute; you can also choose shorter or longer intervals, for horrifying drunks or low-tolerance seated-peeers. You can also set how many seconds into a song playback begins, so your party won't grind to a halt bridging the crashing chorus of "Hell's Bells" to the interminably ominous intro of..."Hell's Bells".
To keep you aware of how much longer you have to keep it together, the display tracks the elapsed time -- but doesn't cap you at an hour. So leverage your existing "Drunk Idiot" playlist into a 340min epic journey that'll take you from Ace of Base to Yngwie J. Malmsteen, before ending just like the powerhours of your youth. With stomach pumping.