Chief Delphi - Designs over the years.

Even though I wasn't around back then, I want to throw in my $0.02 for 2008:

1st penny: Team 148's Tumbleweed - A very unique design, which ended up winning the World Championships with 1114 and 217. Instead of trying to play all parts of the game (Overdrive), they focused on a single aspect of it, and excelled greatly. With a distinct nonagonal base, they mainly circled the field, racking up a large number of points.
More info: http://www.robowranglers148.com/2008.html

2nd penny: Team 1519's Fezzik/Speedracer - An even more distinguished design. Like 118, they chose on a singular part of the challenge to focus on, but did it twice. Splinting their team in two, the younger team members built a small, fast 'lapping' robot like Tumbleweed, while the seniors created a 'hurdler' robot to manipulate the balls with. The 'lapper' was named SpeedRacer, while the 'hurdler' was called Fezzik. They designed their robot to easily change configurations, but unfortunately, FIRST ruled that they were in fact two separate robots, and that the team could only compete with one. After using SpeedRacer in the practice matches at GSR, they ultimately decided to use Fezzik in the competition, and ended up as Semi-Finalists. Luckily, in offseason events, they were able to use both configurations, and even got to enter their robot in both designs as two different bots.
More information: http://www.mechanicalmayhem.org/teamhistory08.asp