Set up a cross-promotion deal with another web business. Allow them to sell your product as a back-end product to their existing customer base. The web business' product should be related to your product or service. If not, it may not sell that well to a different target audience.
Sell your product in a package deal with other web businesses. You can both advertise it and split the profits. For example, if you are selling tennis rackets, maybe you could partner with a tennis ball business and package them together. It's a win/win joint venture deal.
Rent your products out for a set period of time. It's like selling but you get the products back to rent again. You could make more profit in the long run renting your products or services. People today have less money and would rather rent than buy something and only use it once.
Allow people to subscribe to your products. It works best when selling information products, services or memberships. You could charge them per week, per month, per quarter or per year. It will bring in secure residual income. Plus you can sellyour subscribers back-end products for single sales.