Take trash out.
Close windows.
Make sure that climate control and fans are off.
Check fridge for anything to toss.
Make sure that any bills are paid.
If you want to have remote access to a computer, nice to test killing the power on it to make sure that it comes back up.
I do have a light timer, the sort that is usually used to make it looks like someone away from home is present and is operating lights, but I use it for a different purpose, to flip a bug zapper on at night, to zap any moths that make it into the house without having to stare at UV light most of the day. I suppose I could use it for its intended role.