I do raise my rates about once a year. I do mostly AI and text mining, and there is a lot of excellent offshore talent that I am competing with (judging from the people who I sometimes team with). All in all, getting $60/hour working remotely (I live in the mountains in Arizona, a low population area and fairly inexpensive cost of living) is about right. I get about double that rate when I travel and work onsite for US customers, but I prefer to not do that because it interferes with regular life. I also turn down over 80% of consulting offers because I usually prefer spending my time writing (I am also an author) or working on my own projects. I care much more about quality of lifestyle than money.
I work almost 95% remotely for multiple clients across North America charging on the higher end of this poll. I get my work through referrals for the most part, but have learnt the art of closing a lead on twitter.
Have you tried raising your rates?