[0xdeaddead]

Don't create anything new, find a product that people use (and pay for) but are not 100% satisfied with, and make it better.

[mindcrime]

One thing to try is do a google search for "$PRODUCT_NAME sucks". Find the forums and blogs where people rant about the problems with that product, and then use those ideas in your own thing.

For example:

https://www.google.com/search?num=30&q="sharepoint+sucks"

[fspear]

"Making it better" is usually not a simple task, specially for established products.