Finally! I found an inexpensive car charger for the N900. $9.99 at MicroCenter in Houston. It came with two zip-linq cables: one for micro-usb the other for mini-usb. Battery life on the N900 can be a bit short. Having a car charger that works will really solve that problem.
I was a bit concerned at first considering several posts I saw on the N900 forums that only some cables work with the N900. I think the real issue is what the charger tells the cable it's capable of. If it sends the wrong signal the N900 won't charge. This $9.99 beauty does it correctly.