some people work todays some goal, which for OP was the main story line, he finished it, didn't like it much and is wondering if there's anything else in the game that might captivate him so he doesn't have to feel bad about spending $60 on the game that only lasted him through main story line that he didn't like.
OP: one thing I can suggest is doing the main faction quest lines like Dark Brotherhood, Thiefs Guild, Mage College, Companions and then Stormcloaks or Imperial Legion. There's also a number of mods that add extra gameplay mechanics (like wars in skyrim) I haven't seen any new quest mods, but I haven't been looking.
Skyrim is cool because of the amount of exploration you can put into it and keep finding new things, but if you're bored of that then there isn't much else the game has to offer.