One thing I would LOVE to see in Hawken is new game modes. I have a few ideas, and I'm sure others have even better ones. Here are the few that spring to my mind:
VIP TDM
Same rules as team death match but only one player on each team actually counts as a kill. Maybe the VIP player pilots an unarmed VIP mech with crazy agility.
Escort
One team is supposed to protect a travelling vehicle / mech, and the other team is trying to destroy it before it reaches the destination. Either slow or no respawn could make this a nail-biter.
Highlander
Exactly one of each mech type on each team. I suppose this is more like a modifier on existing game modes.
Team elimination
The point is to kill the entire enemy team. When you're killed, you can't respawn until someone on your team makes a kill. Small maps and teams would probably be necessary to keep this fun.
King of the hill
Single player competition. Whomever is at the control point holds strategically superior high ground, and the point is to stay alive and on top for a certain period of time.
Pwn the pros
A very small team of high rank players takes on a large group of lower ranked players in a fight for survival. No respawn for the pros.
Hunting party
An inverse of pwn the pros. A few high level players are faced off against a large number of lower ranked players. The lower ranked player to last the longest wins. All low ranked players win if the high ranked players are killed. No respawns for either side.
Uber
It's one vs. many where one player gets uber buffs. Killing the uber player gives you the uber buffs and makes you the new target. Most kills total wins.
Chain of command
A mixed skill mode where teams are comprised of high, mid, and lower level players. High level players get the ability to mark the map with objectives, and their points are determined by the average score of the lower level players' contributions. The mid level players' scores are inversely determined by the number of lower level player deaths allowed, and the lower level players' scores are based on objectives completed.
Alright everyone, now submit the better ideas!