This stuff will most likely not be terribly useful to those not interested in SpamAssassin development:

Stuff relating to the Incubation process

• IncubatorToDo: To-do list for moving out of the Apache Incubator
• ClaVettingProcess: How we tracked down code owners in order to relicense, and current status.
  

Stuff about scoring

• TenFoldCrossValidation: How to test the accuracy of the scoring system
• NightlyMassCheck: How to run nightly mass-check runs to help with rule scoring
• RescoreMassCheck: How to generate a new score-set (the big mass-check run)
  

More Stuff

• MailManglingInTheField: Information about known ways a mail message can be changed in transit.
  
  

I'm sure more stuff should be added here. Please help out

(DuncanFindlay)