One of the easiest ways of developing traffic is via forums, join a related forum and participate properly (dont just join and post/spam your site). When it is relevant/allowed promote your services in the appropriate channels and you will See traffic spikes which if your offer is right will lock people into your site..
One of the best for this if you are offering real value/clearance compared to other is moneysavingexpert.com, I managed over 2000 additional uniques in 5 days for a phone I was retailing to clear at over 30% less than most people on Ebay (I was trialling the traffic options on a supplier driven promotion). Not only did I sell them all, with 80% of orders coming from MSE but my mailing list grew by 1805 people that I can now mail whenever a good deal comes along and they will promote it for me on all the MSE type sites that they are active on
Ongoing viral traffic...