This is a linkpost for /lw/om1/the_types_of_manipulation_on_votebased_forums/
Self-explanatory title. The list is rather rambling and not terribly comprehensive, but I found it worthwhile nonetheless.
Here's a summary, of sorts. OP also discusses what can be done about manipulation, in a way relevant for lesswrong.
Perhaps the key takeaway here is the useful word 'pabulum'.