My small agency handles everything web-related for our clients, including domain registration, hosting, graphic design, back-end programming, ecommerce, search engine marketing, etc. Historically we have charged all labor at a single rate ($85/hour) because that structure a) makes for simpler estimating and billing; and b) was recommend by Creative Business.
Now, I am thinking about splitting labor charges into different rates for different services. Does this make sense? Do any other shops do it that way?