Links are made like so:
text| (only without the |s) (On that note, if anyone knows how to get the Board to ignore html...much obliged if you'd tell me, because I only know how to do that on the wiki.) Make sure that the url you're putting in has the http:// before it (ie, http://nanowrimo.org; if it doesn't, you'll end up with a link that looks about like this, which is pretty annoying. Putting the http:// gives you the proper link, which is what you want.

On another note, I've just discovered that the method I described above is only necessary if you want to show linked text instead of the url itself; if you don't mind having just the url, adding the http:// in front of it seems to link it automatically, like so: http://www.tumblr.com

And that concludes today's lesson! This has been Experimental HTML with DawnFire. We wish you luck in all your coding adventures...

~DF