This is some definite must read material:

http://www.systemcenterforum.org/mp-authoring-guide-for-operations-manager-and-essentials-2007-now-available/

Here are some others, just in case:

What rules are available in a management pack?

http://blogs.msdn.com/boris_yanushpolsky/archive/2007/10/11/what-s-in-my-management-pack-take-2.aspx

Ops Mgr Tools and Utilities

http://technet.microsoft.com/en-us/opsmgr/bb625978.aspx

Ops Mgr Documentation

http://technet.microsoft.com/en-us/opsmgr/bb498235.aspx

Ops Mgr Authoring site

http://www.authormps.com/dnn/

Visual Studio tools for Office – required, along with Word, to edit Company Knowledge tab.

http://www.microsoft.com/downloads/details.aspx?familyid=f5539a90-dc41-4792-8ef8-f4de62ff1e81&displaylang=en

MVP / Product Group blog sites

http://blogs.msdn.com/eugenebykov/

http://blogs.msdn.com/boris_yanushpolsky

http://blogs.msdn.com/komal/

http://www.systemcenterforum.org/

http://blogs.technet.com/cliveeastwood/

And the blog roll catchall from SysCenterForum:

http://systemcenterforum.org/system-center-blogroll/

Ops Mgr KB Articles

http://support.microsoft.com/search/default.aspx?catalog=LCID%3D1033&1033comm=1&spid=12584&query=&pwt=false&title=false&kt=ALL&mdt=0&res=20&ast=1&ast=2&ast=3&ast=4&ast=7&ast=10&ast

Infrastructure Optimization Model

http://www.microsoft.com/technet/infrastructure/default.mspx

Microsoft Operations Framework (ITIL)

http://www.microsoft.com/technet/solutionaccelerators/cits/mo/mof/default.mspx

Dynamic Systems Initiative

http://www.microsoft.com/business/dsi/default.mspx