Quoting from Codex, the list (so far), includes
- aside – Typically styled without a title. Similar to a Facebook status update.
- chat – A chat transcript.
- gallery – A gallery of images.
- link – A link to another site.
- image – A single image.
- quote – A quotation.
- status – A short status update, usually limited to 140 characters. Similar to a Twitter status update.
- video – A single video.
Strangely enough, themes WILL NOT be able to extend this closed list.