The dot com boom is over but there is still money to be made in domains. I just sold a domain i had for four years for 3000 USD, he just contacted me from my whois record. When he saw i had another domain he bought that one as well for 2000 US. I paid a total of 40 USD each and made a nice profit for those four years.
Few years ago, if you owned a decent domain name, you could generally sit back and wait for the buyers to come to you. Nowadays, you need to be much more proactive in your approach if you want to successfully sell your domain name(s).
At the same time, never discount the possibility of “walk-in” buyers; in other words, potential buyers coming across your domain name during a search, and inquiring about its availability. From you can see on my experinse you need to keep an active whois all the time.
To this end, it’s essential that you keep your Whois record (the record of ownership of your domain name) updated at all times, and free from errors. You just never know who might be trying to contact you! Try to do some linking to the domain, a well linked domain with some page rank will sell better than just a naked domain.