Mark Miller over on EndUserSharePoint.com created a Master Calendar solution using content types. He used content types to define regional calendars, though the same concept could be used for conference rooms - one CT per conference room. On each CT, you could include information about resources available in each conference room, such as capacity, projection equipment, electronic whiteboard, etc. I suppose you could also arrange for catering through these CTs.
Miller uses LightBox to display a view on this calendar. It looks like he's using a custom, blank, master page inside the lightbox so that the calendar can be displayed anywhere.
The trick is that the Event CT is a hidden CT. This means that by default, you can't create a CT based on it! There are instructions elsewhere on the web that explains how you can fix this.
As for taking bookings for conference seats, this solution won't help you as is - more work will be needed. Thinking out loud, I'd be trying to get a CT to look for a list on the site and using this list to limit the seat bookings a room can accept.
This URL will give you a starter on his solution:
Hope this gets you off the mark. cheers