Here are the achievements you need to get recon. Plus you need a Bungie.net profile.

Here is a link to get one:https://accountservices.passport.net/reg.srf?wa=wsignin1.0&rpsnv=11&ct=1250444316&rver=5.5.4177.0&wp=LBI&wreply=http://www.bungie.net&id=42917&sl=1&lc=1033

Here is the list:


Annual: After 9/25/08, complete Halo on 4-player Legendary LIVE co-op, with Iron, and everyone in Ghosts.



Lightswitch: Get to the rank of Lieutenant in any playlist in the new EXP progression system.



7th on the 7th: Enter into any ranked or social playlist with 7 EXP on the 7th of the month.



Brainswitch: Find all the hidden skulls on the Mythic maps(the old ones in halo 3)


Vidmaster Challenge: Endure 25 GamerScore
In Firefight, on any mission, passed the 4th Set on 4-player Heroic LIVE co-op.

Vidmaster Challenge: Déjà vu 25 GamerScore
Completed Highway on 4-player Legendary LIVE co-op, with Iron, and no Hog or Scorpion.

Vidmaster Challenge: Classic 25 GamerScore
Finished any level solo on Legendary, on LIVE, with no shots fired or grenades thrown.(the new ones for ODST.)