MW3 has some really awesome looking hidden emblems and they can be yours.
[newsletter_lock]Most if not all of these emblems are awarded through the completion of Clan Challenge.
Clan Challenges represent both in-game and ELITE milestones that reward Clan XP as well as in-game emblems upon completion. Challenges range from passive milestones, such as the number of days the Clan has existed, to more active achievements, such as winning a certain number of matches with at least six Clan members on the team.
Most Challenges are multi-tiered, with higher tiers rewarding larger amounts of Clan XP. Complete the first tier of a Challenge to unlock the second, and so on up until the final tier unlocks. Completing the final tier of any Challenge rewards all members of the Clan with a new in-game title or emblem.[/newsletter_lock]