Here are some of them and some solutions to work around them
- Spamming comments in blogs or article posts
If you're a blog owner, you have probably seen much of such comments, consisting of totally irrelevant content and a link to some website. Thankfully, Google's Blogger and Wordpress contains comment management system for you to weed out such comments.
- Spamming contact forms that link to your site's users
To reach out to your site's users (if you are running a community site), some might use spam bots to send out solicited emails. However, some seem to be done by humans or very smart spam bots as anti-spam features are bypassed.
- Spamming Forums
If you own a forum, this is a common occurrence. Methods to overcome this include a stringent check on forum members to ensure that their email accounts and IP are not blacklisted. If you use Vanilla Forums, there is a Stop Spam plugin useful for combating such problems.
- Offering to write a free guest post
If you've ever received an email from a certain blogger offering to write guest posts, well, its a trap to get you to check out their website in a bid to boost their traffic. The email consists of a template which is identical for such mails, probably through some marketing spam software.
- Proposed Link exchange
Proposal emails offering to exchange links with high PR rate websites to boost your Google's Page rank. If their PR is already that high, there would not be a need for them to do such link exchange. And who knows what their proposed sites are blacklisted for by various search engines. Furthermore, Google's search engine now places more emphasis on relevant content. Opt for good and quality content coupled with SEO techniques (your META tags, page title, good content structure)
The list goes on and on. Dishonest Proposals and Spam make up the bulk of such techniques to gain traffic for their website. Fellow webmaster and bloggers, beware of such tactics and as a rule of thumb, avoid "quick" ways to get traffic and rely on quality content together with good SEO practices instead.