I guess quite a few people make £xxxx or more per month. You will not make decent money though unless you have very good generics with type-ins or domains with existing traffic.
the only way i have ever made any decent money is by using the link below.
getting even better now they have added a whole bunch of extras.
beets any other parking programe i have tried by miles!!
I have had only bad experiences making money from parked domain names except with Sedo. However you will need goof domain names in the first place, they are not easy to come by these days.