Bus rapid transit. Dedicated, sometimes separated, lanes. High throughput stations. Carefully designed light systems, etc. If you do it right you can get a system that is nearly as good as a subway at a fraction of the cost. A lot of cities in South America, for example, have proven that it works already.
I went to school in Ottawa, where they have a 'transitway' [1] that is basically a series of bus-only highways, though there are some parts that are only dedicated lanes.
I wasn't a daily user but it was decent enough - along the route I used to use most often a bus came every 3 minutes during peak times.
