Allow user to upload avatar instead of using an external URL?
I just started to use commento and I'm surprisingly found that it allows users to use an external link as avatar. This can slow down the loading speed, and can also be maliciously used. For example, any user can create a web service that records Referrer and numbers of visits while returning a valid image. If he leave a comment in all of the posts of a website, he can basically know the statistics data of this website. I think using Gravatar or letting user to upload their avatar might be a better choice.