Wave !
Although Google waves can be accessed by the web, one can contend that the real estate on the browser is quite cramped. A mobile Maemo version would put forward the reading and editing alternatively while keeping links to contacts and navigation handy.
By the way, I've started a public wave at googlewave.com!w+gyolilAgE so anyone can post his/her fav N900 app.
Cheers
This would be a widget or application that is static or activated via a hotkey accross any desktop. The application would search accross all contacts (all relevant information in the contact fields), application names, music, photos and tags on the phone and return results "while typing" similar to the spotlight application on the iphone. Selecting an indexed result would open the associated application based on the search result. For example, a contact that is returned in the search results would open the contact application or perhaps give the option to place a phone call. Another example, a result that is say an MP3 file, options available while clicking on the file might be to play with media player, or open the folder location.
An application like this would greatly enhance the N900 and bring to it a new level of interactivity.
