A family member of someone I know started this online consignment shop. This website allows you to sell outgrown clothes and/or buy new (lightly used) clothes. They only sell high quality children's clothing brands.
http://stellaplusjack.com/default.aspx
To sell your clothes on the site you need to have 10 items and a free-pick can be arranged. Your accepted items will be posted for a national audience, and you'll have the option of potentially making cash, credit, or a donation to charity.
Check it out for details on how to become a client or just shop some great stuff at great prices!