Well, this already exists, really..

- the community user bumps (n) unanswered posts per hour to the front page. Unanswered is defined as no answers with upvotes.

- edits to your question bump the question to the front page.

- new answers bump the question to the front page.

- edits to answers bump the question to the front page.

- after 2 days you can issue a rep bounty on a question which keeps it on the "Featured" tab on the front page for 7 days

The general philosophy is here:

https://meta.stackexchange.com/questions/7046/how-to-get-attention-for-your-old-unanswered-questions