With Google image search being used at a growing rate you can really drive substantial amounts of traffic to your website by utilizing your alt image tags.  Make sure they are descriptive but also that they use high-traffic keywords.  For image heavy niches they can drive tons of quality traffic as I am finding out with my fashion blog, last month I recieved 12k visits from Google images and my adsense has tripled for that site.  It seems three of my images are on the first page of Google’s image search for some very popular terms and those are driving the nice boost in traffic and conversions.

Another great thing that I am noticing so far is that the increase in traffic has not triggered ‘smart pricing’ because the quality of traffic from these image searches are high.  So start going through your websites and find all the older images you have that are missing alt tags and add them in.  The traffic boost will be well-worth your time.