Indeed they do. You might be thinking more along the lines manholes as providing access to water and sewer systems - with either street side pad based pedestels or overhead utility poles providing access to electrical utility services, telephone utility services, and cable television services. In a good part of NewYork City all of those services are underground - along with water and sewer services. In addition, steam is used to power some buildings; Con Edison delivers that underground and needs access to that network as well. Also, there is all the wiring for the FDNY box system and NYCDOT's traffic signal light system. You'll find all kinds of agency markings on the manholes throughout the Big Apple. I'm sure that the ongoing recent rains that don't seem to stop have caused the uptic in fire activity you've noticed. Just wait until after a good rain storm following a good snow storm - when all the road salts used to melt the ice and snow get washed into any manholes that are leaking...that's always fun to watch.