Just thought it might be of interest to mention that I have started using a couple of decent freelance/mentoriing online services, where I can offer my skills to others, on demand. I have been using Codementor for about six months and secured a handful of small paid sessions on it, paying at a similar rate to my usual freelancing one. Clients have been kind in their feedback, and payment is always within a week, via PayPal.
I did hit one client who strung me along with long Skype calls, away from Codementor and thus without any meter running, that ended up being about quoting him for work he needed doing. I reluctantly spent a few hours putting an estimate together, as it was just before Christmas and I didn't have much other paid work going, but in the end he decided to use someone else, without even giving me room to negotiate, and thus completely wasted my time. Something to be wary of in future!
I was approached last Friday via Codementor and LinkedIn by Paul Henn from Toptal, about working with them to gain new freelance work. We spoke briefly over Skype and he sold it to me as a higher class alternative to sites like e-lance, oDesk and fiverr, with global brand clients and pay rates to match. I've just signed up and hope to be accepted on their books soon - more information is at http://www.toptal.com/web