No. There are groups set up for that purpose, such as
Advertising in non-marketplace groups is considered rude, and also
violates some ISP's authorized use policies (AUP) and terms of service
(TOS) which you agreed to when you signed up.
I'm cleaning out my closet, and I found some things I can sell on e-bay.
Can't I just mention it here?
No. That's considered advertising. Mention it in a marketplace group.
The folks there are looking to buy.
I'm going to start a business selling my crafts. Can I advertise my website
Not blatantly. Just posting an ad asking people to visit your site is
advertising. However, you can put your URL in your signature, and can
take every opportunity to help somebody who's already looking.
For example: a poster is looking for a birthday gift, and you make
jewelry. You're more than welcome to respond that you might have what the
poster is looking for at your site. Also, putting a small ad in your
signature means that every time you post, people will see it.
8. Hammock plan
12. Hammock Tying