The more user testing we do, the more we realise its not something you should leave out of a web project.
Every time we test a site there are problems to solve, usually its quite simple, just some content clarification. Sites that are not tested will still have these problems, and you will lose business because of it, so although leaving user testing out is an easy budget reducer, in the long run its going to cost a lot more so I really feel its a false economy.
The way we design and build sites has definitely become more user focussed, so we can usually eliminate the common obvious problems form the start, but a very easy to use website should be the goal to strive for, and you can only get this by watching real users try to use your site, plus its a lot of fun!
We have taken our approach mainly based on Steve Krug's excellent 'Don't make me think' and 'Rocket surgery made easy', both great books and well worth a read.