I just answered a very similar question in another post. Let me copy in the response I made there. I hope it is of some help to get you thinking of things.
Self-made quest examples:
1. Your old friend Baurus has asked your help to confirm the rumors of Mythic Dawn sleeper agents. You're pretty sneaky and clever, so you say sure. He gives you the sketchy documents on what the Blades know and asks you to try and identify the sleepers, find more of them and, um eliminate them if you are sure they are indeed working for the Mythic Dawn.
2. During your visits to Anvil, Countess Millona Umbranox has quite impressed you with her kindness. You feel badly for her lonliness and become determined to solve the mystery of her missing husband, Count Corvus Umbranox. You have always been kind to the beggers. . . perhaps they may know where to start.
3. During your Chorrol Mages Guild recommendation, the rogue mage, Earana quite pissed you off with her threats. During subsequent visits, it has become clear that it is only the city guard that stands between her and fireball in your back. Tired of fearing for your life each time you visit the city of the Great Oak, you decide to eliminate Earana - permanently. In fact, you are quite taken with the idea of her soul, sitting inside a black gem on your desk as a paperweight. . . .
4. During a visit to Pell's Gate, you learn of the plight of Lenwin, a wood elf who found an evil blade called Umbra that corrupted her spirit. You become convinced that if you somehow remove this evil blade from Lenwin without harming her, her life and spirit can be saved. You set about detailed planning that includes damaging the evil blade to the point where Lenwiin will put it in her pack, enabling you to pickpocket it. You believe that the sword can then best be fully destroyed by the lava flows found in the plains of Oblivion.