ZDNet has compiled a list of best of breed Web 2.0 applications which includes two from my compilation.
In other words Microsoft Office alternatives for Web 2.0. Here is the list in brief along with some comments and suggestions.

They also mention a mini-office suit - Zimbra. This is something I am looking forward to try.

I am somewhat disappointed with the list. I would have included at least:
Kiko - Sharable draggable event calendar; interactivity of a desktop calendar, with the added convenience of online access.

Meebo - Multi-colored AJAX powered chat client. It allows you to login to your favorite IM services and provides a MDI web client; pretty neat stuff.

Personally these applications will become much more appealing to me with a desktop version.