Small details can reach huge audiences. Folks used to think that in order to succeed you needed to create a large, all inclusive, solution to a big problem such as Adobe Photoshop or AutoCAD. It's not the case. In the last decade, we've seen that solutions to tiny problems can achieve amazing success. Just take a look at the following examples:
Instagram - focused on a very specific problem of easily snapping and sharing pictures between phones.
Photobucket - focused on one small detail of making it extremely easy to link photos online. They even took it one step further with TinyPic; allowing you to upload a photo and link it up without having an account.
Posterous - focused on a very niche problem of publishing blog posts from email.
WordLense - focused on scanning an image and getting an instant translation of the words in that image.
Shazam - focused on a very specific problem of identifying the music being played at the moment.
Solutions to small problems can change the world. It's the small missed details like these you can capitalize on and build a solution for.