Linkman is a confusing product in search of a problem to solve. It's a bookmarks manager with an exceptional wealth of features. But requires so much effort to use, and is so confusing, that for almost anyone, it won't be worth the effort.
For every bookmark you capture, you can create a rating, type in keywords, edit, and add descriptions. You can then search or browse based on what you enter. But a confusing interface means that you'll spend a good deal of time learning this program. And the effort it takes to input information about each bookmark isn't worth what you get in return.
The bookmarks tools built into browsers these days are surprisingly powerful and useful, particularly the one built into Firefox 3. Given that, you'll most likely not want to give Linkman Pro a try.