A sturdy tripod is a great addition for night and landscape and self timer shots.
There is a vast array of different brands, heads and what not..
A UV filter isnt going to help much but it WILL protect that front glass element from any knocks or bumps and dirt.
I would also suggest a circular polarizer if you start taking more outdoor shots. They can be a great way to change a sky or reflections on the water.
I'm sure some of the more technical folk here could offer some other suggestions, but those two (tripod and circa-pol) were what I started off with!