Yes, an index. So we can find the puzzles that have previously been done on a topic.
All the Hunts from 1994-1997 and 1999-2016 are indexed. 1999 was re-indexed after the April 2013 archive update provided a lot of the missing information and solutions. Many thanks to Aaron Dinkin of Metaphysical Plant for helping get the 2011 puzzles added, and Seth Schoen of Codex for the 2012 puzzles, as well as all the people who have helped fill in gaps in the Mystery Hunt archive.
In any of these ways:
Each page now has a Feedback link at the top which opens a Google Form in a new window which you can use to send feedback. There are also now pages for each hunt and each author, linked to and from each relevant puzzle.
I am considering adding other non-Mystery Hunt puzzle hunts to this index. To be eligible, a puzzle hunt should:
Old MUMS, CISRA, SUMS (one SUMS is missing), the Harvard hunt, DASH, BAPHL, the RIT CS hunts, Mark Halpin's Labor Day hunts, and the Googol Conglomerate game are candidates. PuzzleCrack fails on having a stable website; only 2007 and 2008 are up now, 2008 without solutions. Sekkrets, The Stone, Puzzle Boat, and Panda Magazine are not eligible because access is still limited to what you have solved/opened via a logged in account and/or paid for. TimeHunt and Retrocogitator are not eligible because the puzzles are not online.