There are now two, one from halo reach and one from halo way-point. The first is obtained by obtaining a bull-true medal on an on-line game in halo reach, and the other for earning enough achievements to be rank 50 on halo way-point.
you just do a kill tacular....
Do a bulltrue in matchmaking to unlock the avatar award.
avenge a teammates death in multiplayer matchmaking. [kill the person that killed your friend in a local game]
Achievements and avatar awards.
For the avatar award you need to get a killtrocity (5 kills within 4 seconds of each other) in multiplayer matchmaking You need to be a Captain i think to get the grenadier helmet in the armory
You can unlock Helmets... For everyone in NOBLE team apart from NOBLE 6 (who you play as)
They are two of Jun's helmet. One is for your avatar and the other is for your Spartan on Halo: Reach. The one for your avatar is simply got for "Killed 100 enemies in a row without dying in either Campaign or Firefight. The one for your spartan I'm not sure about.
Unlock Halo 3:ODST's Campaign Complete Achievement. Once you beat the ODST campaign, visit Halo Waypoint on the dashboard to unlock the item.
No you can't get avatar awards in Halo Wars. The only halo game that I know of that you can get avatar awards in is Halo Reach. You might be able to get avatar awards in Halo Anniversary but I don't own it so I don't know.
There are not any avatar awards for Halo 3.
You can only get the Halo games for the Xbox360.
No. There is no Lego Halo, only Megablocks Halo Universe sets.