Everyone has ideas. It's really the execution that matters.

There are two problems here.

First, yes, everyone has ideas, but some ideas are more interesting than others. Common sense, peer review, social news sites, and/or prototyping can tell you which ones are particularly compelling.

Second, execution does matter but that's often beside the point because in many cases the execution is pretty simple anyway. This is particularly true with more original ideas where you don't need to compete on execution -- at least initially.