Megachan does not currently have a large number of rules. This is due to a smaller, more mature userbase and the boards being 'safe for work' - eg no pornography is allowed on the site. Note that while the userbase is small and the rules are not that many, the mods are still active.
There are currently two board groups:
Each group has different aims - Discussion boards' primary purpose is to have discussions and Imagedump boards' primary purpose is to create galleries of images for people to enjoy. Imagedumps in discussion boards are perfectly welcome and vice versa, the only real difference between the boards are their main aims.