11 Things to do waiting in Halo 2

1. Drop and give me 20! Push-ups of course. I actually did this once when I was waiting for someone to finish their matchmade game. You'd be surprise what a difference it makes, especially if you were tired. It really woke me up and made me alert.
2. Read a few Verses. From the Bible. With Proverbs you can read one at a time and can just stop reading when you need to, it's like a bunch of Chinese Fortune-Cookie Proverbs in one place, except they're Jewish.
3. Create a Gametype. One thing you could do is visit http://h2g.halo2webring.com, copy-paste a few of the gametypes you like onto a Word document, print it out, and next time you're just sitting in the menu, you'll have a few gametypes to make.
4. Let's play "Go get a snack". Why not?
5. Watch some TV. After all you're in the right place for it! Just be in a pregame lobby, have it set to "Invite only", invite all who you want to join your party, and then change the channel! Make sure you keep your headset on so that you can hear them when they join the party.
6. Two words: Rumble. Training. I call this one an "all-purpose" playlist. You can ask your friend to message you when he's done and tell him that you'll quit the game and join him when he sends the message. You can also use this playlist if you have 7 people or whatever and don't know what to do.
7. Write a Rap. Just for fun. Try it. It can be about anything, like having to wait for people to finish their game! Then you can present it to them, providing they aren't prejudiced or uber-critical towards you. I find that the less time I've known the person, the more open they are towards me rapping.
8. Manage your friends list. It's always good to be in control of who's on your friends list and who's not. There's a 100 limit to how many people you can have on it, and maybe there are some people you were wanting to send a friend request to.
9. Look at your Recent Players list and leave feedback on bad gamertags. Hey, if you have the time, and aren't getting a snack, it couldn't hurt to do your part in the Halo 2 universe.
10. My life is good. real good... Go away. Read some books! If you've gotten this far down the list, chances are you might be waiting for awhile! Perhaps maybe you could check out some of the chives of this blog, ar-chives that is.
11. Speaking of which, how about working on your Nacho Libre Impersonation?