Name few Black Hat SEO Techniques?

Unrelated Keywords. ...
Keyword Stacking and Keyword Stuffing. ...
Tiny Text, Hidden Text, and Hidden Links. ...
Cloaking. ...
Doorway Pages or Gateway Pages. ...
Bait-and-Switch or Page Swapping. ...
Duplicate Content or Mirror Site. ...
Spam Blogs or Splogs.

Black Hat SEO Techniques

•   Keyword Stuffing
•   Hidden Text and Hidden Links
•   Cloaking
•   Doorway Pages or Gateway Pages
•   Duplicate Content
•   Blog Spam or Comment Spam
•   Trackback Spam
•   Spam Ping
•   Referrer Spam
•   Link Farms
•   Domain Squatting
•   URL Hijacking
•   Social Networking Spam
•   Cookie Stuffing or Cookie Dropping

Some black hat SEO are as below :

Paid link
Keyword stuffing
Article spinning
Duplicate content
Spam comment
Cloaking
Doorway pages
Invisible text.