Yeah, I have the Halo 2 logo.
Go to Bungie.net, and set up a profile. When you're fiddling around with your settings you'll find what you're looking for. If you've played Halo 3 and ODST, you can choose those logos.
If you've played Halo 2, you can choose the Halo 2 logo. Playing CE gives you the Halo 1 logo, or you can just choose the default Bungie.net Member logo which is the 7th Column.
The assault rifle is only for those who played the Reach beta. The Helmet is the hardest one to get: Have the Halo CE PC code, play Halo 2, 3, and ODST.
There's also a weird but cool Marathon one.