This is a tag cloud, a visual depiction of content used on Sweetr. Tags are keywords that people are likely to associate with other members. You can give your photos a "tag" as well. Tags help you find likeminded people. The more searches there are for a particular tag, the bigger that tag is displayed.

Wikipedia describes tags as:

A tag acts like a subject or category. A keyword is used to organize webpages and objects on the Internet. Each user "tags" a webpage or image using his/her own unique tag.

Tags help you find people that have something in common. For example, if you are looking for a date in New York, others may have tagged their profiles with the tags "New York", "NY", etc. The more searches there are for a particular tag, the bigger that tag is displayed.