Personally I'm in the process of starting something and trying to focus on that as much as possible, but I still have lots of ideas. So I have a whiteboard in my office and when I get an idea it goes on the whiteboard. The whiteboard is divided into two sides - ideas that are fun but will never make a penny, and ideas that need further investigation to see if they are commercially viable.
Up until recently I have done contract development work. Nearly all of the ideas that I have that are on the potential money making list come from my work interactions. Either systems I have developed where 90% of the system would work for loads of other companies, or systems that the company wont develop but that the users want, that I think other companies would want.
I am assuming you are a programmer of some description (I assume most people on here are) in which case I think you are in the best position. Look at the systems you work on, Can they be improved, can they be generalised so that other companies may pay for them. It is amazing how many companies will take the $200 a month option where you cannot change the background colour to cyan over the fully customised internally built $20,000 option.Obviously be slightly careful that your company does not have rules where if you invent stuff whilst in their employment then they own it etc - but most companies don't seem to bother too much.
Your startup can accomplish boring business jobs and make money, it doesn't have to be a rip off of Facebook or aggregate Twitter data for you to have a happy life.
Good luck