Congressional Quarterly has a rundown of this cycle's rematches. The Massa/Kuhl rematch was one of the few where the challenger beat the incumbent the second time around.
The article notes that it's very rare for a first-term incumbent to be defeated by the previous incumbent. It examines a number of cases where Republicans who lost in 2006 tried to win back their seats in 2008. None of them were successful. Of course, 2008 was even worse for Republicans than 2006, but there's probably a lesson there for Randy Kuhl.
One challenger who wasn't mentioned in the article is Darcy Burner, who garnered a lot of attention on the Internet and raised big money via ActBlue. Burner lost her rematch against Dave Reichert [R-WA-8], even though she outspent him this cycle. Burner's campaign was often mentioned in the same breath as Massa's, since she lost a tight 2006 race by 3%. Burner actually lost by a slightly larger margin in 2008.
Comments
Darcy Burner was also associated with "A Responsible Plan" http://www.responsibleplan.com/ , a plan for extricating the US from Iraq, which Eric Massa was also involved with. My impression is that Burner seemed to grab more of the limelight while Massa did more of the work.
I got that impression, too.