http://en.wikipedia.org/wiki/Flip-flop_hub

I don't think they are particularly expensive. Some bikes come with them stock.

And if you are worried about things breaking, well...with regular care modern derailleurs are not prone to explosion. But you are correct in that the less parts you have, the less parts you can break (and the less for people to steal if that's a problem there), and with no cables and things routed everywhere, there are less things to worry about.

I personally like to vary my rides, but I mostly ride the same routes. It's amazing how much different the same route can be at different cadences using different gear ratios. Some days I like to use the biggest ring up front, the smallest ring out back, and use my strength to haul ass (sometimes even standing up on the flats like I'm riding a ridiculously-geared BMX bike). Most days (especially after those aforementioned days, when my legs are really sore) I like to keep it in the middle ring up front, somewhere around the middle ring in the back, and pump my legs fast for a good cardio workout, and to work all the lactic acid out of my muscles.

But, that's just me. To each their own. You could also get a similar effect by varying your route on a FG/SS I suppose, but I just like the options multiple gears gives me.

I'm excited to get a new road bike too (I've never had one before, it's on order!) but I went the geared route. Like I said, I've never had/wanted a single-speed after my first multi-geared bike.

*BUT*

If you want to be a hipster, you definitely don't want to show up at the party with derailleurs and such all over your bike. And make sure you have a decent messenger bag...Chrome, Timbuk2, etc. Make sure you spend over $100 on it or people will laugh at you. It also helps if you can strike the perfect balance between originality and accepted "fixie" norms for your bike. It should be fashionably ghetto, simple yet quirky, pretty without trying, etc. etc. You'll have to ask a hipster for all the details, because I'm not well-versed in the culture. From what I understand, though, hipsters are judged almost exclusively on their bike, and what they wear while standing next to it, so be very careful in your selection of both.

EDIT: This probably won't fit in with the hipsters, but if I was going to get a FG for $800 I'd get this one (and add brakes to it) for no other reason than it's like the bike I just ordered, and the red on black looks really interesting:

http://www.feltracing.com/09-catalog...es/09-tk3.aspx