Ask HN Freelancers/Contractors: What rates do you have?

This is mainly for freelancers, contractors, and, well, anyone who hires their services out to clients. What rates do you have, how do you differentiate, and do you charge more or less for different types of task?

And now for the background: I've been working with a Lawyer to get a standard contract and general terms written up for future client work, and the question about rates was asked.

"Normally," I said, "I will charge $X/hour for regular contracting work, and $Y/hour for very short notice or emergency work."

"All contacting work is worth the same amount?"

And that got me thinking: some stuff adds significantly more value for a client, and is much harder to do, where as other stuff isn't complex, doesn't add much value for the client, but needs to get done. Here's what I have been able to come up with so far for different rates:

* Standard Contracting rate.

* Emergency rate: Covers anything that would normally be done under the Standard Contracting rate, but which has been requested at very short notice. It will be higher than the SC rate to offset my own costs.

* System Architecture rate: Planning, designing, requirements discovery, and technical documents. This will be significantly higher than the SC rate because the value for the client is much higher for the time spent.

* Re-factoring rate: Cleaning out old code bases, removing old/legacy/un-used code, adding documentation, etc. This will be lower than the SC rate because it takes a long time, and is more of a "long term investment" type of job.

So what rates do you have, and do you charge more or less for them?