Link annotations create hyper-links to other parts of the same document, to pages in other PDF documents, to web addresses, email accounts or to other files on your system.
You can create link annotations by issuing the a command from the menus, or popup menu, and dragging a selection on the page over the content that you want linked. If the content contains text, the link will be made to fit the text neatly. You can also select some text first and then issue one of the link creation commands. Once the link is created you can set its destination in the inspector, by double clicking the annotation.
If you select some text containing a web link or an email address and then create default link (command-option-L), then PDF Nomad 2 will try to extract the link and use it as the link target, so that you don't have to type it in manually.
PDF Nomad 2 has provisions for automatically linking cross document references to their targets (like the link in the screenshot above).