- First and foremost, we've always been able to link the names of items by shift-clicking them -- just open up a chat line by hitting enter, and then shift-click anything in your inventory, and a clickable link will appear in chat. This works in almost everything but "Say," and even then, the name will show up, it just won't be clickable.
- As you may have seen in the link above, patch 2.4 made spells and abilities linkable as well. You can also go into your professions screens, and shift-click either the item (if you want to create a clickable link for the created item) or the recipe that makes it (if you want to show someone what mats are needed for a certain craftable item). And quests are shift-clickable, too.
- Outside of the items and abilities you have access to, there are also a number of addons that will serve up links for what you're looking for. Atlasloot is probably the most popular (and it's actually a standalone database of items with the extra bonus of being able to link them all), but there are addons like Linkerator as well that are specifically designed to hook you up with links of all the items you see.
- Outside of even the game, Wowhead implemented a linking service a while ago that lets you click a button in your browser that then gives you some code to paste into your WoW chat panel. That way, you can link items without ever seeing them in any game or database.
- And if you want to get really crazy, you can jump into the API, and create your own itemStrings, which are small clippings of code that will return item information from the WoW client. If you look at the Wowhead copy and paste code, you can see these at work -- they'll require some coding knowledge on your part (and some extra research to figure out how it all fits together), but if you know how to create an itemString, the item ID of the item you're looking for, and how to output that out to the chat channel, you can make links of any item you want.
That last one is pretty advanced -- with the default system and the addons linked above, you'll probably be able to cover all of your item linking needs anyway. A game like WoW
is all about getting gear -- examining what you've got, finding out where more is, and getting better wherever you can. A solid knowledge of how to link and share item information will help you do just that.