1) I recommend that you try the articles and forum at
www.longhaircommunity.com Their styling suggestions are classed not just by length but by hair type.
2) French pleat (the one where you put your hair into a ponytail with one hand, twist it utnil it starts to want to double up on itself, then sort of tuck it in a long vertical roll against your head and pin it there)
3) French braid. If you don't want anything hanging down, you can tuck the end upwards inside the hair where it's plaited against the back of your head.
3) Dutch braid (like a French braid, but the plaited bit sticks out because you plait each strand under instead of over).
4) Heidi/ballerina plaits - one each side, then take them around your head and pin in place.
5) Garland twist - take a small section of your hair (slightly above one ear) and begin twisting it against the side of you head, while working around and picking up more hair as you go. When you've gone right the way around, hide the ends and pin in place.
6) Garland braid/plait - as with 5 but plaited in, similar to how you'd do a French braid, but working sideways instead of downwards.
7) Half up half down do - with variations on whether you plait bits of the top or bottom, and whether you twist the top bits or not.
8) Divide up your hair and make as many skinny plaits as you can be bothered with, then twist them, bun them or whatever for a slightly different look.
9) Divide your hair into 2 tangle free sections, and tie a reef knot with them. Probably better if used to hold your hair back than to keep it up when active.
10) Rope braid - it's difficult to explain but you can see plenty of how to pages if you google for it. Basically you twist a few sections of your hair, then lay them against each other in the opposite direction to the one they're twisted in and they form a rope as they relax against each other.