There is already a webpart for this but it shows subsites etc, which is not the requirement.

What I need is a webpart that will list the Site collections a target user is a member of, and it must be robust enough to work with groups and AD.

I tried to check permissions however on closed site collections that the user who is viewing the list is not a member of won't show.

What I need is a way of making this transparent, so that any user can see another users site collections.

Any more ideas? I have tried several, and they either run into permissions issues or are too heavy in processing to be viable.

**[update]**
This is more of a challenge now than a NEED, best slickest answer gets the goodies.

**[update 1]**
This solution needs to be robust enough to check for a specific permission, this is due to certain sites in some collections are blocked, but some are set to read, this is done with groups, and there are open and closed site collections, which means the users get read access tot he root collection but cannot access higher ones, and sometimes are blocked totally.

The issue with this was that a user requirement was to simplify the view for permissions with users and to only show 3 custom groups, meaning we had to recode the a mass quantity of built in web parts and replace them with custom ones, also limiting views.

With this in mind, a user is given a certain group access in a site collection to be able to have a different level, by default they all get "Non Member" with gradually higher permission types. Default built in groups are not used in this installation so RunWithElevatedPriviliges was not used and we used impersonation to an AD user we created to do the same thing, different site collection types have different setups and this allows us to modify the granularity of the situation. (End users are a pain when they want to break out of the box.)

**This is a 100% customised deployment and everything works perfectly, except the site collection membership display is slow with the current method, and I want to make it better!**