I've done this before - but caveat emptor - conference pricing can often be at or above the higher tier of rates you'd get by shopping around on your own unless it's a huge conference. I just returned from the ACS Clinical Congress in DC - given the sheer volume of attendees, I compared the conference rates with my own corporate discount code and found little difference. We ended up staying slightly out of town and rented a car and saved hundreds.

I've used meetings to 'bust' sold out periods in Las Vegas, including the National Broadcasters convention where I actually registered to get access to the hugely discounted rate - I registered for free as, believe it or not, someone in the "non attending" category.