I use Cufon to display non-system/non-standard fonts. Typically no more than one or two per page.
Cufon works...about 99% of the time. Periodically I load a page and see ugly bitmaps. Then later it works fine. No code change underneath - I've also seen the same thing at other sites (that I don't design). Big companies, too.
From some research, it sounds like this is browser bugs. I'm guessing something doesn't work correctly in the javascript rendering and so you get the fall-back or default fonts.
Again, it's not common...but I worry about the impression it makes when a new visitor comes and sees an ugly site.
Is there an alternative to Cufon that is more 100%? Other than limiting myself to the global fonts only...