I went browsing Meta SO for any profile rules, and it appears there really aren't any. A user's profile is a reflection of the user, not a reflection of the site.
You can put pretty much anything in there, even profanity, although since it is a reflection of the you, you may want to consider carefully what you put in there.
Rules for Profiles?
The person is known to us.
However, the profile is where a user can say (almost) what they like and this doesn't come anywhere close to crossing that line.
I'd just ignore it - most people don't view user profiles anyway.
Gravatar is a third party service for global avatars:
Your Gravatar is an image that follows you from site to site appearing beside your name when you do things like comment or post on a blog. Avatars help identify your posts on blogs and web forums, so why not on any site?
The benefits are outlined in this blog post:
I’ve used Gravatar for a while ...
If you go to the accounts tab on your profile page - https://stackoverflow.com/users/720176/amit-dwivedi?tab=accounts you should see three links/buttons:
Copy Stack Overflow profile to all Stack Exchange accounts
Clear all Stack Exchange account associations
Copy Stack Overflow login credentials to all Stack Exchange sites.
Click on the first ...
You are identified to a particular Stack Exchange site by your user id on that site.
You can change your user name without fear of losing your reputation. The only restriction is that you can't change it again for 30 days - so choose wisely.
Go to your profile page - https://softwareengineering.stackexchange.com/users/39058/chac (for example) and click on ...
You have up-voted 124 deleted posts. Such votes do show up in your totals, and also count toward various badges; they have the additional advantage of not counting toward the daily voting limit.
They don't show up on your profile's votes tab, because that would mean showing you links to deleted posts - that would equate to giving you broken links on your ...
I asked for this on Meta Stack Overflow way back in June 2009.
The only thing to come out of that appeared to be the accept rate of questions - not on answers.
I agree it would be nice statistic to have. Not sure about the badges though.