I made this plugin for a friend who had a specific problem: let users to upload an avatare and some profile data without changing the theme or using external serivces (not all users are able to use external services).
At the first, since it would be something like a community, I suggest him to use BuddyPress, but he cannot find a theme for his blog, or better he didn’t want to change the theme.
So I wrote this simple plugin, User Profile, to let registered users to upload a photo and manage some additional profile fields (dates, texts, choices).
The plugin, when available, change the standard Gravatar generated by WordPress (the great part of themes use it) using the uploaded picture. If you theme uses the get_avatar() of WordPress, User Profile should work on your blog.
To see the effect, look at the first (my) comment below where there is a my avatar and my country as extended field.
If you want to register this site (this plugin works only with registered users) you can start from the profile page.
To see the effect of a comment after you setup your profile, leave a comment here, please. Test comment won’t be removed on this post.
To get User Profile, see the official page.