Kernest is one of the first good options for using embedded fonts in a website. Unlike projects like Cufón or sIFR, Kernest takes advantage of @font-face embedding, which is now supported by Firefox, Internet Explorer, and Safari.
One of the problems with @font-face at the moment is that Safari and Firefox support font formats like OpenType and TrueType, while Internet Explorer only supports Embedded OpenType. The usual workaround is to supply a different format depending on the requesting browser. This is exactly what Kernest takes care of for you.
Not only will it serve the right file type depending on the browser, it will only serve the font files when the request comes from a domain name tied to that particular font. Many of the current selection of fonts are free, but in order to make them available to your domain, you must activate them. Based on my brief use, this is a very simple process, requiring only a user account, and adding new domains is completely effortless.
I’ve been trying Kernest out for a few days now, and have found the experience very pleasant all around. I don’t know much about what TypeKit’s model will be like, whether they will have some fonts available free of charge, or if there will still be a charge for the service. If not, Kernest looks like it could be a great free alternative for projects without a budget for fonts.
And in the meantime, I highly recommend giving it a try. There are already several serviceable fonts on the site. I’m currently using Droid Serif from Ascender Corp.
Update: I’ve since switched to Heuristica.
Update 10 Dec 09: In case it isn’t obvious, I’m using neither Droid Serif nor Heuristica anymore.