Change Menu Item's links Dynamically, per page basis I've been looking for this for a while, but found no solution.

What I want is: Whenever someone visits to a user's profile, say http://mysite.com/user/1 there should be an item available in Main Menu, with the link: http://mysite.com/custom_module/1

Here, I'll be dynamically changing the menu item's links based on the current page. How to achieve that?

Thanks.
It depends on how exactly you want to change the links, but views can handle most links if you configure the contextual filters correctly.  Basically, just display a link to the content as the field and then set your filters and contextual filters (getting the argument from the node/user) as you need.

If you just want to change around links for user profiles, there's also the me module.