As everybody already stated about the liability, etc...I think we used to get a hundred or 125 per game to rent out on free play per day. I can tell you from being the actual guy that had to move it all....it sucks. Everybody wants you there in a 10-minute window, you should be able to roll in a pool table, jukebox, 2 video games, and a pinball by yourself through the backyard in July, set it all up, avoid the DJ and the 300 drunk party "guests", everything is going to work 100% the first time, and oh, by the way, you should KNOW where the stuff is going, didn't the lady on the phone TELL you this? Oh, and a nice cold beverage on the way out the door after sweating off your a$$ to make THEIR party better? Not a chance. Oh, yeah, and can you pick it all up at 6:45 tomorrow morning too? (usually this comes as you're dropping off equipment at 10 pm).
Sorry to have the jaded opinion, but I've been there plenty of times. The other problem I've run into is when you get there, the game works fine. You get a phone call at 1 a.m. saying your game isn't working. Now, whether or not it actually is, they want it for free, or they want you to show up and fix it, and then give them a discount. Now, you've done all the work for the grand total of nothing. Yeah, it's happened.
If it's someone you know, sure, go ahead. Otherwise, it may not be worth it. Just my opinion.