Having specialty services can help expand the customer base and increase income. It is a sure way to get your foot in the door to offer follow up or maintainence services too. You can make more per hour power raking/aerating than mowing/trimming.
The LCO's here tell me that they are able to pay off an aerator in less than a months work - even less time for a power rake! These services are also an impulse buy so they are able to get away with charging a higher price. Mowing is not the same.