If you've got some good ideas that you don't mind giving away, post them here. If you see an idea you would like to build, it would be cool if you mentioned it in the thread; that way like-minded people who might otherwise not meet have a chance to work with each other.
1. A site where a developer can do some basic domain modeling, select a database type, programming language and framework, and the site will generate a compressed file (zip or tar) that contains the wired up site with all the basic CRUD forms. Premium options could include authentication being built in to the apps, or reporting suites, or all sorts of extra features.
2. A better way to find breaking news that actually has significance. The big news sites have decided that celebrity divorces are equally as important as earthquakes that cause massive casualties, so following breaking news through them has become an enormous waste of time. Find a way to determine if breaking news is actually news by way of real-time search through things like twitter. Make it configurable so that users can specify what sort of news categories they're interested in (finance, world news, US news, politics, etc).