I have added a menu item to the Personal Actions menu by creating a CustomAction like so:
<CustomAction
Id="myCustomAction"
GroupId="PersonalActions"
Location="Microsoft.SharePoint.StandardMenu"
Sequence="1000"
Title="My Link"
Description="This is my custom link."
>
<UrlAction Url="http://www.example.com/" />
</CustomAction>
However, I want a dynamic URL. There is a URL parameter that changes based on the current user. How can I make that happen? (By the way, this is an external URL, and not part of the SharePoint site.)