Just thought I would share a tip that helped me, it's not rocket science but I have been trying it and has good conversions. For one of my niches the ad in the sidebar was having a hard time converting and selling with different offers. So I just created a cheesy quick 300x250 banner in photoshop that says Amazon Deal of the Day 50% off New and Used (my products). Then I searched "daily deals" in Amazon and sorted it by my department, then the navigation links under the search usually has deals or sales deals or something like that and I just linked to the daily deals. Some departments don't have daily deals so you can just link to whatever you want. Doing that ended up being my best link earner on that site, so give it a try and see if it helps.