I was hacking on a little side-project, and found that most lists of torrent trackers are full of defunct trackers, or lots of dupes. I spent a while going through all the lists on the first few pages of Google, compiling them into a giant list, de-duping it, and then writing some quick code to test all of them.
Also, an aside: "/announce" on the end of a UDP URL doesn't make any sense. It's completely ignored at the protocol level, so I normalized entries by removing it.
I don't endorse any of these trackers, nor suggest you use them for committing copyright infringement.
These trackers all respond to at least some scrape queries: