Tuff part is finding a tool that can let a users manage ACLs with a GUI tool. WorkgroupManager does this for 10.4 Server. So far the only tool I have found that can do this with 10.5 is TinkerTool System.
I've owned TTS for quite some time. Never touched the ACL tab though -- maybe for good reason.

I went searching on macupdate for others. Came across a GUI app called Sandbox for editing ACLs. Screen shot looks interesting. However not yet certified for Leopard; so doesn't change your remark about only thing in 10.5 being TTS. But something to keep on eye on?!?

http://www.mikey-san.net/sandbox/