Something that has been on my radar for a few years but I wasn't willing to splurge to buy the dedicated software or spend the countless hours developing protocols for GIMP colorization is this.
I see today that someone has now developed those protocols and something for PS too plus the GIMP stuff should translate easily. They can be found over on the right side of the page mentioned.
Looks like I might start trying to dabble a little bit with the techniques we'll see.
Some great stuff people are doing with old B&W...makes me wonder about doing 'modern' B&W now and colorizing it for effect.
Some of Roger's Once at the Old Great World would be cool.