To generate a formatted reference on the fly, drag any citation from the middle column of your Zotero library into any text box (a WordPress post, a message board, a GoogleDoc):
The style in which citations are generated can be changed from your preferences menu (Settings > Preferences > Export).
To create a bibliography from a whole collection, right-click on the collection folder and choose Create Bibliography From Collection:
Choose your citation style and output method. Note that the Output Mode function is not currently working: