I think the warning / banning system needs enhancing.
1) Would be nice to see time bans - suspended members are then unbanned automatically after say 24 hours, 7 days, 28 days or however long the ban is for.
2) The ability to ban members from individual forums / categories. This would save creating a new group that excludes posting rights from a forum and adding a member to it.
3) Also maybe a three strikes and you are out system - if a member gets a warning it displays beneath their display name a yellow card, three of these cards would generate a ban. Other members would see these warnings, and it might shame them into towing the line. Viewing of these warnings could be visible to all, members, mods or admins as IP's are now.
