Trading Services for Cash
How to Approach Companies/Individuals
Be non-invasive and simply offer your services in exchange for some of theirs. You could even offer to do something for free, and if you can obtain results, offer your services going forward at a price.
The potential is there. Remember, these companies / individuals are likely looking for cost effective methods of earning money online, and if you can provide this for them then they will jump at the opportunity (especially if they can offer their services rather than money in exchange for your work).
You may get recurring work if you not only offer extreme value, but also quality service. Companies are offered online marketing and website services all the time, but the offers are usually very expensive and do not fit into their budget.
If you make a fair offer, then you are much more likely to get the job! DO NOT undercut your time however...you do not want to work for free. Most companies do have a budget for this sort of thing.