2-Quick translations app. (Better than the dictionary in the E71)
This is a nice Idea which I was thinking of earlier, using the google translate API would be useful.
People enter their trip and time and they will get a listing of people who happen to do the same trip (who are also registered, of course) and will be able to request to share a ride with them. You can implement user ratings, requests (accept/refuse)... you can extend it also for plane trips where people want you to carry a piece of luggage for them - but you will have to think about drug dealers, etc.. who can use that for bad purposes.
Very nice idea which I just added on my list too :)
Oh and another one: using GPS you can make an app that will help 2 people (who have GPS enabled phones - most probably both nokia) to find each other in a crowd, using directional guidance or maybe a minimap.
I like this very much but not sure about the implementation, added to my list :D
an easy google application that uses google/yahoo search engine , images and translations
Added on my list :)
Please keep the ideas flowing, whatever pops into your mind as an idea just post it as it may be a winner, who knows? ;)