TwitterMinder allows you to automatically post Twitter messages from your Google Calendar. TwitterMinder will check your Google Calendar for events that are occuring in the next hour, and if it finds any they will be automatically submitted to your Twitter status.
AmzWish is a widget to display your Amazon wishlist on your blog or webpage. Users can click on an item from your wishlist and purchase it for you.
Map Feeds, not just single locations. Try FeedMapper.
Upcoming.org already provides a useful set of RSS feeds and a great API. The only problem is, their RSS feeds are useful only if I know the metro code. I used their API, along with RSSBus, to create a set of dynamic RSS feeds for Upcoming.org events. I can now control the results of an event search by using the querystring in the feed URL itself (i.e. http://www.textbox1.com/upcoming/search.rst?location=27502).
Try it here.