Patch the view engine to do alternative sorts. This will include both the lower level couch_view* modules as well as the fabric coordinators.
Patch the view engine so we can specify options when returning docs from cursors. We'll want this so that we can delete specific revisions from a document.
Need to figure out how to do raw collation on some indices because at least the _id index uses it forcefully.
Add lots more to the update API. Mongo appears to be missing some pretty obvious easy functionality here. Things like managing values doing things like multiplying numbers, or common string mutations would be obvious examples. Also it could be interesting to add to the language so that you can do conditional updates based on other document attributes. Definitely not a V1 endeavor.