[whswhs]

Sure! In fact I included an "urban shaman" template in GURPS Fantastic Cities. There are even traditional spiritistic beliefs adapted to big cities: for one, the Roman idea of lares, spirits who in the country watched over the boundaries of land areas (for example, of farms) but in the city protected houses, lots, or neighborhoods.

I think there are several types of spirits you might look at:

Rural spirits that have more or less adapted to survive in cities
Rural spirits that have taken off in a big way in cities
Spirits of new, distinctively urban things, such as technology, specialized land areas, or even the city itself (Dea Roma and all)

I'd also suggest taking traditional symbolic gestures, such as giving someone "the key to the city," as actual evocations of magical and spiritual forces.

Bill Stoddard