Some small, but extremely interesting new things over the last few months in the field of genuinely useful web services:

Writely - a web-based web processor.

Foldershare - free file storage and synchronization. Recently bought by Microsoft to fit with their new Windows Live service, so I wonder how long it will stay free.

Yousendit - not that new, but brilliant.

Wordpress.com - hosted version of the free and open source Wordpress blogging platform

Foxmarks - Free bookmarks synch that actually works.