Their website contains a wealth of excellent free content on SEO in theory and practice - and many in the industry use this content even if they are not SEOmoz customers. These resources establish SEOmoz as a "thought leader" in the SEO field and they earn much positive awareness and industry respect as a result.
A good place to start is their free SEO guide for beginners:
SEOmoz is a great example of how a strong inbound marketing program can accomplish many things (increase awareness, create positive brand perception, increase sales, etc) if done correctly.
They're also a good follow on Twitter for the latest on SEO and Search marketing (at @SEOmoz).
