The new Google maps for mobile (GMM) impresses me a lot. Have a look at www.google.com/mobile/maps/
It is an application that you can download to your mobile phone, in my case a Qtek phone with Windows Mobile 5.
It is a scaled down but very usefull version of the full version of google maps (GM). It shows roads or sattelite images, and it can plan routes. What makes it even more usefull than GM is that it can get your current location from your mobile operator, or a GPS if you have one. It can also navigate from your current location to an address in your contacts list. As with GM, you can do location based searches, like “find nearest restaurant”. In comparison to car navigation systems, it lacks spoken instructions. On the other hand, those systems do not give you sattelite images.
I don’t have a GPS yet, but this may be the reason to get one. Currently it shows my position as the position of the nearest GSM basestation, and updates that as I move along.
You probably only want to run this if you have an unlimited data plan, you’ll go through 1 MegaByte of data real quick. For me this is no issues, as T-Mobile provides me with a flat rate GPRS plan for 10 Euro/month.
There are a few minor glitches, but nothing that prevents me from using it. Here is my wish list. Share your locations with GM. Search special location types such as parking spots and gas stations. Links in search results that lead to sites that can usefully be viewed on a mobile.