Well, Black holes could function as extremely heavy stars without light, effectively making for a huge amount of jump points in an otherwise totally dead system.
I think this is a (rather common) misconception re. black holes.
Yes, you need a certain mass to form a black hole (2.3 sun masses, I belive), but the stars, that blew up and thus created the black hole were a lot (and I mean A LOOOOOOOOT) more massive than the resulting black hole. blowing something about 90+% of its mass away when it goes supernova. Only the (relatively) small remaining mass is left concentrated in the black hole. I seem to remember a number of 50 to 100 sun-masses in order to form a 3 sun-mass black hole (All those numbers are from the top of my head, so might be a bit off, but not by an order of magnitude)
Also, black holes are not the "oh, a black hole in 30 lightminutes, we are doomed!" phenomenons, often described in fiction. If our sun would suddenly turn into a black hole, it would be night on earth some 8 minutes later and all life on earth would die some time later for lack of light/warmth, but the earch would continue on its path around the "sun", the moon would continue to circle the earth. A black hole is only mass, just concentrated so much (forming a singularity), the escape velocity is higher than the speed of light.