Back in the Win95/Off95/IE4 days, M$ started shipping with its systems (and making available on its website) some fine fonts optimized for screen display, to be used for web design mostly. It was nice, because the alternative (especially for web page design) was Arial/Helvetica and Times Roman. Andale Mono, Verdana, Tahoma, Trebuchet MS, Georgia, Comic Sans, Arial Black, Impact — they might not have been the greatest thing going, but they beat the alternative (sort of like Windows itself).
Then in 2002, M$ got out of the biz, for a variety of reasons (including because folks were downloading and using them on Linux, it seems). While various bits can still be found online, those foundational web fonts are now restricted to being passed on from site to site, install to install, like some sort of oral tradition.
Now, it seems, that M$ is getting back into the font business, with a new set, and a more stringent license regime. Which is keen, but I sort of wish they were using the “old” ones in the list, too. Further Balkanization of presentation models is not what the Web needs right now.
(via J-Walk)
More info here, along with a link to the M$ core fonts on SourceForge.