Wendy Kerr mentioned in her talk some websites where she gets cost-effective resources from. She recommend testing them out with a small piece of work, and then if you are happy and your trust is building, grow it from there.
Job Bid Sites - where you post the piece of work you want completed, and people from all over the world bid on it outlining their experience and pricing.
Virtual Assistance Services - these are like a personal assistant, but are not located in your office. Again for most of them you can pay as you go.
Wendy has used Brick Works for 6 years and they have done a lot of typing for her, created power point presentations and completed research. If you google Virtual Assistants you will also find UK and US based organisations.
Ad Hoc Staff