Advantages of Disc Brakes

Disc brakes are becoming increasingly common on all kinds of bikes these days. There's a good reason for this. In a word they're awesome. Here are some of the advantages of disc brakes.

Increased Stopping Power - With a bigger surface area of contact, you get more stopping power.

No Wear - You're not wearing out your rims by creating a nice grinding paste with grit/mud.

They Look Bad Ass - Lets be honest here, they look pretty darn cool, and that's never a bad thing. 

Consistency - They're far less prone to get clogged with mud etc, so you can rely on them to be there when you need them.

FAQ

Q. Is the increased price worth it?
A. Yes.

Q. Are they essential?
A. No. They're really nice to have, but a good set of rim brakes will also do an excellent job.

Q. Can I get them for my road bike?
A. Not really. You can build up a cyclocross bike with them, but you won't find a purebred road bike with them (yet). 

Q. Can I use disc brakes from a mountain bike on my Cyclocross bike?
A. If you're using drop bar shifters, no you can't. The cable pull is different. However you can buy the road specific version which are excellent.

Q. What's the difference between hydraulic and mechanical?
A. Mechanical disc brakes use a cable to push/pull the brake pads together. Hydraulics use fluid. Hydraulics tend to be more powerful and you have better modulation. If you can get hydraulics they're usually the better choice, but there are some excellent mechanicals around these days.

Q. Can I get hydralic disk brakes for a Cyclocross bike.
A. Not yet. The body which governs cyclocross has only just approved disc brakes for use in races. They're in the works I'm sure, but are probably a year or two away from seeing the light of day.

Q. Who makes good ones?
A. Avid make the best (IMO).