I am a big fan of Flickr so I thought I give some examples of how it can be used to generate traffic, build links and increase your visibility in the search results.
Traffic Generation with Flickr: In March I wrote a blog post named Traffic & Link Building With Flickr at my personal blog. I showed how much traffic one can get from images that become popular in Flickr. On the overall scheme of things, it is not a ton of traffic, but it is a nice amount of traffic for a new site. What do you need to do to direct traffic from Flickr to your site?
I typically add descriptive hyperlinks that encourage people to click from the image to the blog post. Yes, Flickr allows you to add hyperlinks in the description, which is very useful.
Matt McGee also recommends making your screen name your Web address. I personally don't like that, but it probably does work from a traffic perspective.
Link Building with Flickr: As I showed above, Flickr allows you to put direct links in the description area of your image, to your site. Those links are currently clean HTML links, and there are not nofollowed. So they do pass some link equity. I assume, once it gets completely abused, things will change with that.
If I were you, I would use them in the manner of traffic building and not link building. This way, you are a bit more safe when it comes to "abusing the system."
Increasing Search Visibility with Flickr: Not only do you benefit from the links you have to your site, but Flickr images also tend to rank well in the search results for a certain period of time.
For example, as I described in my pursuit to sell my monsey condo. I achieved pretty good rankings for the keyword phrases I was looking for, in order to help sell my condo. Not only that, the figured I would title my Flickr images slightly different to target a slightly different keyword phrase combination. And as you can see, at the time I am writing this, they rank in the top two for monsey condo:
Those are just some ways to use Yahoo's Flickr to build traffic to your site through search.
Forum discussion at Search Engine Watch Forums.