why donīt you try hosteurope.de ?
Their servers are located in Germany.
They seem to have a pretty fast and reliable network and also offer something called WebHosting Pro ( "hosteurope.de/produkte/WebPack-Pro" ). It is like a vps but wihout the need to do the administration of a vps. The plans have already pretty much traffic included. Also their managed servers have a 100mbit unlimited connection.
We have servers in Leaseweb, hetzner and rapidswitch and we recommend all of them. If the speedtest site is used for many european countries I recommend you get a server from leaseweb as they have peerings with more countries. If the speedtest site is used mostly from Greece then any of these providers will work for you.
Do you need to install a script on the server or do you just need a server to store the files that will be down- and uploaded ?
Did you think of using a CDN or a storage solution for your speedtest ?
For example amazon s3 or any other CDN ? I also think that rapidshare could be a nice option for you if you need low prices for traffic. They offer something that is called TrafficShare and could be just right for you.