Not entirely sure on what you are actually asking us here?
Are you looking for links to where to post them?
or if you simply should or shouldn't post them?
...either way, just to name a few
www.deviantart.com is a great site for all things design, be sure to post them there and
www.behance.com Register for a portfolio and you couldn be connected to thousands of people interested in your work.
as for the 2nd option, the answer is yes!, defiantly, more publicity for your work and the chance to improve on them. As fo prints, deviant art offer print service, and I believe flickR (
www.flickr.com) are connected to MooPrint - although I may be mistaken. Be sure to post your work on as many networking sites as you can.
Good luck.