Firefox 3.5 will be launching this summer (betas available now!) and will include support for downloading and using regular TrueType and OpenType fonts referenced from a style sheet.
This is also supported in Safari 3.1 and later, and apparently by the latest Opera betas as well.
It might be helpful for some language wikis to link in a free font this way, when standard fonts supporting their script are often unavailable. Right now on such sites there tends to be a little English link at the top such as ‘font help’ leading to a page like this telling you how to download and install a suitable font.
Internet Explorer afaik still only supports converted embedded (EOT) font files, which would require that we can either get our hands on an existing .eot version of each free font, or be able to generate one ourselves.
Note there’s an old feature request with an .eot copy of a Tamil font, but we never had authorship info on the font or cross-browser support, since .eot is only supported by IE.