Try using THREAD tags instead of URL tags. This will take up a
lot fewer characters. For example, instead of
[ url=http://forums.alpinezone.com/12996-belleayre-1-20-2007-a.html ] 1/20 [ /url ]
you can use
[ thread=12996] 1/20 [ /thread ]
(of course take the spaces out; those are just to make sure it displays)
You'll get a
link out of vBulletin automagically, you just need to grab that number. I find the easiest way to get it is to just look at the URL in the browser address bar. So for your signature, you're looking at 12996, 13021, 13237, 13413, etc. You'll save a lot of characters on 17259 (your backpacking trip).
You can link directly to posts, too. Hover over the "permalink" in the top right of any post and you'll see something that says, for example, "go to #post205541 on this page. Well, you can just grab that number and do
[ post=205541 ] text [ /post ]
and again you'll automagically get a link like
this one which is to your question.