Markit!

Currently support FCPX only. With the clean and simple mobile app, you can focus your eyes on what's happening on set. Once you've set the project up, type away. Don't even want to type? Just hit enter and a blank marker will be placed there. It is not a sync app, just a metadata management tool. You don't need the $500+ devices to sync timecode. You'll have a time accuracy of markers under a second, which is good enough to save a lot of time when you get into your assembly edit. Drag and drop the marker files from the mobile app and a fcpxml with the creation date metadata, this app will match up the markers and export a new fcpxml.