I was reading Ecorazzi, a neat green site, and noticed that they have a sidebar image of their weekly Twitter giveaway. Yep, every Thursday at 3pm they give away a green item. Very cool! Letting your readers know that you are thinking of them will really drive them to continue to read and support your blog. Depending on your niche, contact stores and brands and ask them to supply you with a giveaway item. In return, you are doing a little free advertising for them. It's a win-win for everyone!