Although six percent is the accepted standard for real estate agent commissions on home sales, you can pay less. Generally, if you negotiate a lower rate, you can expect a lower level of service, but you want to specify that level of service in the contract before you sign.
Some real estate businesses even offer a menu of services that are available at varying commissions. But before you gun for saving money, consider whether you're really willing to put up your own signs and staff your own open house. If it's not a problem, then go ahead and set up the abbreviated service contract. Just be sure that you and your agent are both clear on the services that will be contractually provided.