Not a whole lot, at least right now.
- They feed into some analytics that mods & employees use to keep an eye on the general health of the sites.
- They're put into the public data dumps and Data ExplorerData Explorer for perusal by all and sundry.
- They influence the selection of Greatest Hits.
There were some 10K tools as well (now hidden) intended to help flush out posts that were getting exceptional amounts of anonymous feedback; we may bring these back in some form eventually.