I’m still undecided, but I think that Active Desktop on Windows (or, at least, the concept of using a webpage for your desktop) is perhaps promising.
After a little bit of screwing around, I’ve got a news headlines page in my background (see it here; maximize for full effect), with stories from the BBC, NY Times, Slashdot, and Dave Winer. Unfortunately, there’s no way to have it automatically update more than once per day (hourly would be better), but this is a good start. Then again, following links sometimes crashes the whole computer (running the allegedly robust Win2000).
Of course, the value of this is somewhat negated by applications that maximize to take over the entire screen. Access is a particularly egregious offender.
I’m surprised that no one from MS has tied AD in with Outlook to put new emails and upcoming calendar and to-do entries on the desktop. It seems like it would be an easy thing to do (though easier if Outlook dealt in RSS or some other kind of XML or ical).
Still, I wish I were able to use a less sluggish and plodding web browser than IE6 (it’s the only allowed/supported option here). I may have a mac on my desk soon, though; Safari definitely fits the bill.