Diablo III is about to come out, and I anticipate a lot of questions about it. These questions (and their answers) are likely to refer to skills and items from the game, so they are likely to link to them.
There are multiple places where one can link to, such as the official Diablo III Game Guide and the unofficial DiabloWiki or Diablo III Database. Furthermore, some of these sites publish a script which can be used to add tooltips when hovering over links pointing to them, something which could be very useful in this site.
There was a meta-discussion regarding which resource site to use with Terraria, and while I'm not sure it's something we'd want to enforce, I would like to encourage our active members to be consistent in their links with D3 as well. I think it's best to use the official site - not because I think it's better, simply because I have more trust in these links being more resistant to link rot.
In addition, that means that whoever is interested in the game can install this userscript for Gaming SE and enjoy the tooltips whenever there's a link to the official site.