Mike Industries' blog post describes Scalable Inman Flash Replacement (sIFR), a technology that allows designers to use custom fonts in HTML text by replacing it with Flash movies. sIFR uses JavaScript and Flash to render text using a font specified by the designer, while still being accessible to search engines and users who do not have Flash enabled.
http://cufon.shoqolate.com is a JavaScript library that allows designers to generate custom fonts on web pages by converting them to vector graphics. It uses canvas element of HTML 5 to render fonts and improves the quality of text rendering in comparison to traditional web fonts.