If you have one of those great Pocket PCs with VGA screens (HP hx4700, Fujitsu Siemens Loox 720 etc), then you might be interested in this beta version of PDAMill's popular Gamebox Solitaire.
Also, the excellent Flux Challenge is available in beta version for Microsoft Smartphone platform.
In other news, I have been playing Stuntcar Extreme for Pocket PC over the past two days and its damn addictive. The only problem would be there are no way of mapping buttons to the accelerator/brake/view/nitro controls. But its a minor issue and probably Fathammer decided to implement on screen control to ensure compatibility to all Pocket PCs.
There is also a version for Nokia's Symbian Series 60 platform. Both costs US$19.95.