Tappin' to the base...
If you are running an ecommerce store online, then Google base is a fantastic way of generating some excellent free targetted traffic for your products. You will need to sign up for a google account to use this, simply click login on googles homepage in the top right.
All you have to do is simply tell Google about your products via the use of a text document.
It is the first thing I suggest to my clients as the only cost involved is your time. Although it can be a) time consuming and b) can be technical.
Alot of the ecommerce packages including JShop, OScommerce and Zen Cart to name a few have modules / addons available which export your products to Google base, which makes life so much easier.
Googlebase can also be used to promote services and classifieds too so may work for other businesses also.
Head over to Google, type in a search and hit "Shopping" to see where I am talking about.
What are you waiting for?