Various mashups and the ilk have been fast-and-furious in the past year. I've played around with my own map-application interfaces, while also appreciating many of the various schemes for UI that have popped up. The following is a short coverage of some of the nice interfaces I've come across.

Windows Live Local is the newly rebranded Virtual Earth (think Keyhole->GoogleMaps). It has some nice overlays, the ability to add pushpins with annotations, tours, and ooh, right-click support.

Wayfaring is a Ruby/Rails web application utilizing GoogleMaps. It's got a very nice layout with map, set of links along the right-hand side, comments below, and the ability to handle tracks.

Hunting Legacy Online, despite its unlikeable (to me) subject matter, looks like a really nice interface for creating map annotations, layers, etc. The purpose is to tell a history of your hunting trips. However, the same premise could be used for geneology, family trips, photographic shoots, etc.

Maps for Mapserver is a very slick interface for mapserver, which is typically static. It doesn't have many bells and whistles, but is a great demonstration that you don't need to be locked into one of the "Big Three" (of online maps) in order to have a nice mapping interface. They use MapTools to perform the GIS magic.

Waymarking is using static Tiger maps currently, but i'm a fan of their sidebars and isometric icon graphics.