Are these URLs not the same website?
Function like tiny url but rain.xxxxxx?
And another very useful feature as a part of this one: allow the user to declare a whitelist of domains, where any URL parameters will be ignored (e.g., I use bookmarks to catalog people on facebook. I want to see that a person is on the catalog when I'm on any of that person's FB pages - so I would want to simply ignore anything that comes after the ? sign in the URL)
lemme know if you want any more input or clarifications on this!
In future will be possible to enable this mode - all new links will be automatically normalized