Depends what you want to use it for. Anyway, you can have multiple bitcoin addresses for different purposes.

On top of that, while I wouldn't rely on this cryptographically, the relationship is one-way. Gravatar links email addresses to gravatar images, but it's not intended to link in the other direction, so the same is true for any information stored in the gravatar.

You can use my system to reply with encrypted text to a comment on a blog post without knowing the email address of the person you're replying to, only their gravatar image.