My website informs potential customers about the service and cleaning process inc example prices etc. I advertise the address in Thompsons etc including links from other directories on the internet.
I cannot say that it brings in floods of work, but has been worth it from repeat business from a small amount of customers and one off jobs.
I would say £500 to £800 per year from website.
Just booked a £200 job for next week from it!
If your web site is welcoming, informative, professional and also fast loading (doesent take ages to upload) you will get work from it.
You have to make sure it is seen and connected to relavant links.
John