Add Linked Images To Gallery
Makes local copies of all the linked images in a post, adding them as gallery attachments on the post itself.

Crossposterous
Crossposterous will cross-post your WordPress blog post to your Posterous site. You can choose whether to post a teaser with a link back your WordPress blog post, or cross-post the full content.

Hoverswap
Hoverswap allows you to create swapping elements, whose content is swapped for its title when the user hovers over them. Excellent for foreign language learning and translation web sites.

Prev-Next Keyboard Navigation
Press the “J” key to see the next post, and the “K” key takes you to the previous post. Automatically load the “next” or “previous” page when you hit the end.

Tweetpost
TweetPost is a multiuser plugin which allows wordpress publishers to automatically tweet their new posts to their Twitter account. Tweets consist of a message (“New post from @user”) including a reference to the author’s Twitter name, the title of the post, and a bit.ly shortened link to the post. It also supports Twitter’s new Tweet Button, and a few configurable options for how it is displayed.