my best sales come straight from the parked page inquire link direct from end users, sedo, afternic, bido, godaddy premium listings are some other options.
If you are good at negotiating, then having someone contact you about your domain is best. If you don't feel comfortable with this then listing the domain somewhere with a set price is better. Using a broker who can help you with pricing can also be good, but your fees may increase.
Namepros is really, really great and pretty good for selling, but don't expect to get much for your domains. It may just be me, but it seems that most things sell for wholesale prices or lower. My last auction for about 10 domains paid me $4...!