I always pre order US DS games, for this reason: I want to make a great collection, with great games, and if I do like the GBA, I would have to spend +500$ today to buy all the games I missed... Plus US boxes are prettier than Euro box.
I pre odered some Nintendo GameCube games by past, especially because I won 10€ on them.
I thought to pre order Prince Of Persia 3 on GameCube, but I know I will find the game the d-day, even 2 days after... so I forgot this idea.
I'll probably pre order Zelda The Twilight Princess, it will be probably be THE game in 2006.
So if I pre order a game, it is in one hand to complete day by day my handeled collection, in other hand to play game I want to play the d-day (for GameCube) or couple of days after for PS2 US (time to receive it in Europe; I chose to buy a PS2 US because I am using as a DVD Player for the Zone 1 and all the games are in 60Hz, and of course, most of time they are out in US before Europe).
On Neo Geo, I only pre ordered KOF03, Metal Slug 5 and Samurai Spirits 0