This is a question I never get asked outright, so I thought I'd ask it here. People don't often realize that the commission is actually part of the marketing strategy for their property. Aside for paying for service from your listing agent, the commission also goes to attracting more buyers' agents, each of whom may show your house to multiple sets of buyers. The more buyers who look at your house, the better the chance of getting multiple bids, and that's when your actual sale price goes over your list price.
If you need to sell fast and need to make as much as possible off the sale of your property, you may want to consider increasing the commission to outside broker rather than lowering the price. For instance, if your property is listed at 300k, instead of lowering it to 290k, you could increase the commision 1/5% and pay the buyer's agent $1500 more, which is considerably less than the 10k you wouldn't receive otherwise.