On our blog we have run a number of competitions, usually with a small prize donated by a company in our niche. This has included DVD's, food hamper, books etc.
These generally generate a huge surge in traffic, we share the posts on sites dedicated to listing competitions, and related forums. We offer extra entries for people who share, like or follow us, gaining quite a number of extra hits and sending out good social signals to the big G.
In exchange we include information on the company offering the prize and links to their site (no follow has always been fine).
We do have a recognised "brand" in our niche, and are followed by a number of companies who are glad of the extra publicity for a low cost. We get the traffic boost from a wide range of sources/user IP's and for no cost other than a blog post and asking for a prize.
This is only really going to work if your niche would have low value items connected to it that people would genuinely want to win and that you have a good circle of contacts from which to ask for a sponsor.
Worth a try if you are able to.