A recent request from a client was to improve the Views 2 exposed taxonomy filter so that it intelligently hides taxonomy terms which aren't related to any of the content returned by the View query. As anybody who has spent time poking about in Views vast configuration panel will know, this isn't possible through the existing Taxonomy handler.
Stackoverflow.com had a fewposts from users requesting the same functionality, and replies from others saying it wasn't possible with Views 2. Well the good news is: it is possible, right now, without hacking Views.
Ixis worked with Manchester based agency Worship Digital to produce a great multi-media based community site for the legendary Haçienda club brand in Manchester (UK).
The project included the usual News section for promoting upcoming activities and history of the nightclub, and alongside this an events area which allowed pinning an event on the world map using a custom Drupal CCK field.
Whilst doing some R&D around Twitter related services I've noticed holes lacking in APIs for a number of services. It's not just myself that groans, support queues, mailing lists and Twitter are full of people grumbling about lacking functionality from the services.
Today it was the turn of photo hosting service Twitpic who provide a great basic API service but lacks any ability to extract all images for a specific user through the API. A minor bonus is that each user of the service gets an RSS feed of their uploaded images, although it only serves the last 20 images - 20 being the number of photos shown per page.