Any useful strategies for finding a Nether Fortress?

Anyone have useful strategies for finding a Nether Fortress in Minecraft's Nether?

I got into the nether and wandered around for quite a while, but didn't find anything. I'm not sure if there are giveaways (I was looking for large building-like things in the distance). I've got a map, and have explored a small, but not unreasonable part of it. Any idea how many fortresses a single map might contain?

Solution 1:

There are infinite nether fortresses in the nether. They spawn in rows every 200-400 blocks along the world's North/South axis.

Once you find the first one, just keep walking north or south from it to find another.

Solution 2:

In my experience, you just got to look around a lot. They are big and black, and generally the main levels reside at a Z value of ... 64? I forget the exact value. The other piece of this, is if you are significantly higher than that, you'll just miss them (unless you can look down through big gaps in the netherrack), if you are down at the lava level, and the fortress extends down to that level, the fortress looks like a big black blocks, and you have to build a ladder or tunnel up them to get to the interesting stuff.

I felt like I had to look forever to find my first one. Keep it up, and you'll find one pretty soon.