Answer
SIL is really two parts:
One - SIL is a low cost, high quality Self Improvement membership site dedicated to providing help solving life challenges and a platform for learning how to create the life you want. Membership features a library of textbooks in the PDF format (many with audio recordings and mindmaps), and hours of audio seminars, interviews, and teleconferences, and video all designed to help you solve challenges you face on a daily basis in areas of personal development (health, wealth, relationships, career, family etc).
In addition, the lounge offers step by step guidance on creating the life you desire.
Two - SIL is a blog offering free help and solutions and a free self-improvement evaluation quiz.