I was just fiddling with the links on our very old ecommerce site and realized we don't use any tooltips (those mouse-over popup bubbles that go by various names) on links. I don't think they existed when we began about 12 years ago, and I know there were browser compatibility problems with them early on.
Tooltips should be a good way to enhance the meaning of links and also to add some SEO power by sprinkling in a synonym or two. I felt stupid for ignoring them so long.
But I see that most of our competitors don't use tooltips on links either. Those merchants include some very sophisticated sites.
Do you use tooltips for links in your ecommerce site? Are there disadvantages to using them? I suppose that file size was a concern years ago. What's the current thinking about tooltips and SEO?