The collection of fonts available to a web developer is depressingly limited. I remember reading long ago about TrueDoc, as a way of shipping fonts alongside a website - but it seems to have languished. Has anybody used this, or something similar? Is it supported by enough browsers? Am I missing a good solution?
Note that a responsible web developer does not use fonts that are only available on Windows (and especially ones that are only available on Vista), nor do they use a technology that isn't supported by at least the majority of browsers.
Update: As several people have pointed out, there's nothing wrong with providing a list of fallback fonts for people who don't have the specific font you use. I do in fact always do this, and didn't mean to suggest that this was wrong.
While my question was badly phrased, what I meant was that a designer should not make too many assumptions about what the client will have available. You should plan for how all users will see your site, not just for people using your own preferred setup.