There's another common thought I hear voiced often: That you have to come up with an idea that no one else has done before - a green field idea. That's wrong. Competition in a space is often a sign that there's something valuable there. Competition is energizing. A lot of the ideas I'm thinking about exploring already have established players or startups - it's just that I think I can execute much better than them.
Yep. There's a quote from Bob Parsons (of GoDaddy fame) that goes something like (paraphrased roughly) "Don't be afraid to enter a crowded market, just be better than everybody else."
This is kind of our mindset at Fogbeam Labs, where - depending on how some details shake out - we'll be competing with everybody from Jive Software, Yammer, Alfresco and Broadvision (among others), to Salesforce, IBM, Cisco and Microsoft.
But that's fine. We have an angle to pursue that we think will let us make some inroads against those guys, and we're spoiling for a good fight. Heck, as far as I'm concerned, those guys should be sleeping with one eye open. :-)