I think that if you want a semi-pro camera, then your options are pretty much the Canon 60D or 7D, or the Nikon D7000 or above. You don't want to get caught in a situation where you tell someone that you bought a semi-pro camera, and show them a point and shoot.
Look to spend around $2500 and above for a semi pro camera (including one or two lenses).
If you're looking to just take decent pictures, then a lot of the recommendations given earlier are great - even the iPhone recommendation. But try not to tell people that you have a semi pro camera.