I have a wiki site with multiple libraries (Sharepoint 2010). How can I link pages together from different libraries?
The standard, simplest way of doing this is to use built-in wiki functionality:
Start by tapping [[ then wait for the drop-down menu which should among other pages in the same library at the end of the menu 2 options -Lists and Views. Use keyboard Arrows (very important: DO NOT USE MOUSE as the menu is quite Sensitive) to select LISTS and once selected simply press TAB key. This should show a list of all libraries/lists (if you have more than 8, start by typing a part of the target Library name which shall filter out only those matching). Again, once selected, ONLY VIA Arrow keys, press TAB again to see all Items from the library, which could other pages.
Once done, simply press Enter and is shall automatically close with ]] while putting the actual link to the selected page, something like [[Name of page|link text]]