Inevitably, when designing a Web site compromises must be made to maintain usability and accessibility. This is especially true of fonts. While there are endless possibilities for layout, graphical elements, and so forth, there are really only a handful of fonts to choose from. Most of these are run-of-the-mill fonts and are pretty boring: Times New Roman, Arial, Courier, Verdana, Helvetica, Lucida, and sans-serif. That's pretty much it. Until recently, if you wanted a custom font on your site, you would have to include it as a graphic. But thanks to the help of sIFR (Scalable Inman Flash Replacement), you can now use any font you want to, have it render as editable text, and everyone will be able to see it.
There are multiple benefits of using sIFR in terms of SEO and design. Often times, sites will have their main heading in a different, more elegant font than the rest of the content on the page. Using the <H1> tag in conjunction with CSS classes limits you to only a few fonts for an <H1> tag. sIFR allows you to render any font you want in real time. Because of this, your <H1> tag will actually have text in it instead of an image, which carries much more weight in the eyes of the search engines. As far as design goes, you no longer have to sacrifice that perfect font for one that just "works." Your pages can have all the designer flare you want them to without sacrificing spiderability.
The downside to this method is that page load times could take a hit. While it should never be a very noticeable lag, sIFR text usually renders last simply because of all the behind-the-scenes work that goes on. Though sIFR is a great small-scale fix for rendering typographical fonts on a page, you shouldn't overdo it. Try not to render anything more than headlines. You should try to keep the number of times sIFR is used on any one page to under ten. More than this, and you might start to notice a lag.
Overall, sIFR is a great solution for sites to render typographical fonts. It was also designed to accommodate future browser upgrades, meaning that as soon as Internet browsers feature a richer font list, sIFR can easily be lifted out without disrupting anything else on the page.