Disable some features in Admin

Check Out the Role Scoper plugin: http://agapetry.net/news/introducing-role-scoper/

Role Scoper is a comprehensive enrichment for capability enforcement and administration in WordPress. Assign reading, editing or administration roles to users or groups on a page-specific, category-specific or other content-specific basis.

Update
From your comment, I dug a little further. This article explains adding custom roles and abilities: http://www.wphardcore.com/2010/ultimate-guide-to-roles-and-capabilities/. Seems very useful.