You work so hard finding forums and message boards that match your interests & will target your potential customers. Let those posts, not only answer questions but also promote your site, blog, store or squidoo lens.
Most forums either don't allow posting your web address or have only 1 thread for you to post your site. HOWEVER... most allow a hyperlink (they have the "url" in the design bar when you post) Hyperlinks are picked up by Google, Yahoo & the rest of the search engines. This is the REAL reason you want to try to hyperlink as much as possible.
Here is an example:
Say you are on a "moms" forum & I sell Candy bar wrappers for parties.
Someone comments on getting their 5 yr old's birthday party ready....
Say this forum does not allow websites... so I can't say "see some party favors at www.candybarwrap.com
What I might say is.... I bought some cute personalized favors & they were the hit of the party!
Hyperlink a KEYWORD in your post.
" My Sister just had a baby"...
My reply may be.... "I saw these ADORABLE Custom watches that you can put a picture on... great Holiday gift.. I bought my mom one with the grandkid's pics on it"
"What did you do today" thread
DON'T say " I blogged new recipes & added products to my video store
Search engines are seeing keywords & the fact that they are linked to your site.
For message boards that don't have the hyperlink ability... then you just have to rely on a signature.
So just be sure to follow rules on different forums but I have not had any problems so far.
Happy posting all!