Interesting question. The only time I've heard of using nofollow is when you link somewhere else (I'm new to this so there may be other uses for it as well). Here's an article from a single dad blogger about why you would want to use nofollow when posting a "badge" or something from another blogger: Dad's House Blog
I frequently link to other blogs in my posts, and I don't use the nofollow in those links, but for badges and images that are in my template itself, I do.
Wow! I didn't know about this! Thanks for the article link. Now I don't know what to do about the badges, personally I like them, but I don't want them sucking my blog energy. I also don't feel right about doing his quick fixes.
How do you nofollow just the one link? My blog program asks for pages, but not individual links, badges, or widgets.
I disagree with what Dad's House is saying about badges. The reason people use badges is to get more incoming links, true, but linking to another blog or site doesn't take away "Google juice" from your blog. In fact, if you don't link out to other sites, Google gets suspicious. It's all about karma - if you link out to a site that lists your blog, too, or that you like, why not? Share the linky love!
Sometimes I just want to stop caring what Google thinks. I like sharing "linky love"! I love badges, my husband calls them Blog Bling! When I first decided to blog, I didn't even know one could make money doing it. I found out when I researched how to create a blog. If I still didn't know that now, I wouldn't be worrying about these things... :-(