hey, i'm looking to buy a new mountain bike and someone suggested a singlespeed to me. i need a bike to get around town and to do a little bit of xc riding, all in a relatively flat area. any suggestions or tips?

You need to be more specific.

Surly 1X1

Go with a bike with gears to start once everything starts breaking or not working right. Turn it into a single speed. Then the fixed urge will set in & before you know it you'll be a skinny tire fixed freak like the rest of us.
Happy trails have fun.
Cheers

If your looking for a complete cheap bike, the redline monocog is kinda cool... and it's available as a 29er. But if your gonna spend some money, I might second the surly 1x1. Gary Fisher for '06 though came out with a vertical dropout, disc compatible, steel, eccentric bb, with a derailer hanger hardtail. Its available as a frame or complete geared bike I believe (sram x9 maybe...?). That could be a cool route.

Rigid singlespeed MTB will suit you fine. Nice fat tires (2.3) should give you enough cushion, and the bike will be light, fast, and bomb-proof. You have lots of choices. Bikes mentioned above are great, but also look at:

IRO Mia
Bianchi M.U.S.S.
On-One Inbred

Where is the OP from? Rigid is pretty unpleasant in some parts of the country but great for others. I tried it down here for a while and it wasn't really an option for me. Back home I would probably consider it if ss was a viable option. One of the guys I ride with does use a rigid but with a 3.0" front with really low pressure but that would be even worse then suspension on the road anyway.

If you want a bike thats going to be locked up around town but still good on the trails I would go for the redline flight monocog. Its still really cheap but is Al so you don't have to worry about the paint when you lock it up.