I wrote a while back about building your own geocoding engine. The Tiger/Line dataset has some flaws as a geocoding service, most notably that once you get out of urban areas many addresses simply cannot be geocoded.
Recently, I was sent a presentation outlining other options (pdf) which seems to be a great place to start an evaluation. The focus is on Lousiana--I'm not sure how the conclusions would apply to other states' data.
Posted by moore at March 22, 2006 07:01 PM