With the new bounty system anyone can attach a bounty to a question. When a bounty is placed, a question is also bumped.
Take UserA and UserB both with over 200 reputation. They are either owned by the same person or are friends. UserA and UserB post an answer on each others questions. Well, the question asked by both of them got a few upvotes but they feel they should've have gotten more attention. So UserA attaches a bounty to his own question as does UserB. At the end of the 7 days they award the bounty to each other, hence no reputation is lost between them and they both get on the featured tab and on the front page for a while. They can then repeat this multiple times.
In order to combat this, I propose a new feature-request that bounties count as an edit entry. This way after more than a couple times of doing this the question will become community wiki as well as the answers.