Would anyone want to post a download to their top 10 songs? They have so much material, it would be awesome to give everyone a quick feel of why they're so special. I only know a few albums so I wouldn't be qualified, unfortunately. I do plan to see their farewell though.
This is really just personal preference, but my favorites would be something like:
2) All Ages Shows
3) Campaign for a Better Next Weekend
4) Saddr Weirdr
5) Future 86
6) Side Projects are Never Successful
7) 493 Ruth
8) The First Time I Met Sanawon
9) Fresh Attitude, Young Body
10) Syke! Life is Awesome!
Like someone else said, it's all available for free on their website. Good albums to start with are Scrambles or Vacation.
Also, this show is going to be amazing, and I can't wait for it, but I'm also going to be real sad afterward. I've been going to BTMI shows for so long...