I decided to scour The Green Papers, and come up with a list of primary challenges against Democratic incumbents in the House and Senate. Most of these take place on what I call Super Tuesday 06, September 12th.
Disclaimer - This is a full list for information, and does not necessarily constitute an endorsement from little old me.
Of course, there's Jonathan Tasini vs Senator Clinton:
http://www.tasinifornewyork.org/Also, in New York, there are challengers for Towns, Engel and McNulty (links in order of incumbent)
http://www.barronforcongress.com/http://www.greenforchange.com/http://www.jessicaflaggforcongress.com/http://www.raleigh12sep06.com/In Maryland, there are challenges to Albert Wynn and Chris Van Hollen.
http://www.donnaedwardsforcongress.com/http://www.deborahvollmer.com/In Minnesota, a challenge for Collin Peterson
http://www.challengemn7.org/In Rhode Island, Jennifer Lawless is challenging James Langevin
http://www.lawlessforcongress.com/In Wisconsin, Chip Denure is taking on Ron Kind for supporting the war:
http://www.protectthetroops.com/In Florida, a challenge against Kendrick Meek:
http://www.goneree.com/In Massachusetts, Phil Dunklebarger is taking on Stephen Lynch. Something of the lone right-winger in the otherwise progressive delegation:
http://www.dunkelbargerdemocrat.org/In Washington State, Hong Tran, the only challenger to Maria Cantwell who refused to be bought off:
http://www.hongtran.com/In Hawaii, DLC'er Congressman Ed Case is challenging Senator Akaka. And Neil Abercrombie also is facing a challenge:
http://www.house.gov/case/http://www.immigrationlawhawaii.com/Remember, The Green Papers is your friend ;)
http://www.thegreenpapers.com