I was just reading an article that seemed to say this was one of the best tactics for increasing your business earning. Do you practice upselling? Offer cheap basic services, but the add on for "upgrades" for more emails, larger space allocations, etc? I have upgrades listed on my site, and they ask you again when you register electronically. I'm thinking of adding something to my rebilling notices, like "Running out of space? Click here to double the size of your hosting package for a fraction of the cost." or something like that.