Yesterday night I happened to listen to the BBC programme called The Bottom Line. Mr James Dyson was on. For those who are not aware, he is one of the finest engineers around. His company makes many things, most famous of all the Dyson Vacuum Cleaner. So, he was asked what gets the creative juices flowing for an entrepreneur. Mr Dyson said "anger". Anger at something that does not work well. Chanelling that anger to come up with a better solution is creativity, it is the entrepreneurial spirit (in software, it is sometimes called scratching an itch). Great to listen to. Check this video where Mr Dyson speaks about failures.
Here's one other note on entrepreneurship I read: Paul Graham at YC making things clear for applicants.