A few things that can cause a draw (some already mentioned) some even when they are off ....
- Smoke/co detectors
- TV's & DVD players with instant on
- Radios, not only ones with clocks but with other features that may look like they are off but still be running to maintain memory/features.
- Inverters
- Battery / solar monitors
I do wonder if some of the appliances like fridges, hot water tanks, generators do not pull a small phantom draw. Each on there own would be minimal but together could add up.
I think the best advice is to pull your fuses and then check for the draw, that will isolate the accessories and only leave the line from the battery to the charging/power center.