I'm not sure I'd call this one finished but it's quite usable now. The purpose of this script is to provide a way to quickly filter images using voting. It is tested only in Google Chrome. If you're using another browser, I'm not sure if it will behave.
If you make a bookmarklet out of the included minified script (at the bottom of the pastebin entry) and click it while viewing search results, it will first downvote all blacklisted images returned. This makes using -voted:username tag and refreshing the first page after voting properly load in fresh, visible results. Blacklisted images currently displayed manually should not be affected. During this step, it also pre-loads all of the preview size versions of the images on the page.
Next, the images will display in a keyboard-controlled lightbox style slideshow. The controls are simple: upvote, downvote, previous and next. You can use arrow keys, ijkl, or wasd, or even = and - for upvote and downvote respectively according to your preferences. Voting will advance to the next image. Enter or space will open the current image in a new tab (and advance the slideshow), which is required to view flash animations. Each time the slideshow advances, it will automatically scroll to the currently viewed image on the search results page. Pressing any unbound key will close the slideshow, and it will automatically close once the end of the results have been reached.
Pros: quick voting! My hope is that using tools like this, image scores will become a more reliable indicator of how many people like or dislike an image rather than how many people had very strong feelings one way or another.
Cons: Stripping e621 down to upvote/downvote removes the user from viewing the tag list. This method does provide a quick way to open the post for editing, but it's not very useful for frequent tag edits.
I welcome comments, as well as additions to the provided script if any code-savvy users have input. I've not gotten around to it yet, but adding in a favorite option bound to 0, F and H is next on my list of ideas.
Updated by abadbird