Any kind of plug&play data visualization system that allows you to install a region and a Web-side app which can then be cross-tabbed to internal corporate data (e.g. sales figures, say) and which then displays some kind of in-world prims/visualization tool.

May or may not be dependent on the MediaAPI

Built on the basis of MediaAPI availability. Be able to pull documents in from SharePoint repositories, modify, and track edits and versions made while in-world.

Ability to create 'virtual meeting rooms' same as internal calendars have 'real' meeting rooms. Be able to book those rooms and have them 'blocked off' for virtual meetings.

Widget that can be easily plugged in to blog engines that allows in-world display of posts (maybe a tick box? "Display in virtual environment"?) and the ability to comment on those posts in-world with the results being displayed on the blog itself. For use by enterprise who have internal CMS systems based on blog software like Wordpress or Expression Engine.

For those folks using "enterprise Twitter" - rework current SL Twitter tools for Yammer?

Look at the JIVE API, such as with Clearspace, and figure out how a "Go3D" button might work for enterprise using JIVE either internally or externally. No idea what other integration ideas might work, but JIVE seems like a large enterprise app.

Not sure if this is an 'app' exactly - but some kind of better integration of e-mail and in-world messaging instead of just an auto "send to email" thing for IMs.