I have some widgets on my site that allow other site owners to embed a tool on their site. The widget is served in an iframe and the embed code includes a link back to my site. When I first created these widgets I used my keywords as anchor text. Now, in the era of Penguin, I have changed the anchor text to say, "Tool provided by myurl.com".
Something in my gut says that I should be doing something different. It's an obvious pattern that Google could likely discern as a linking scheme. I see a few options:
1. Provide the embed code for the tool and ask the site owners to make their own link back. This way they will use their own idea of anchor text which is more natural. However, 95% of the site owners in my niche are not tech savvy and would not know how to link to me.
2. Randomize the embed codes so that there are a number of possible anchors that could be used when a site owner copies and pastes the code.
3. Remove the embed code altogether so that people who want to recommend the tools will just link to the site. The benefit of this is obvious as it is very natural, but it also means that fewer people will see the tools.