There are the books "Samba 3 by Example" and "Samba 3: The Official How-To Collection" which may be available in your samba package, or even installed in /usr/share/doc/packages/samba/.
If you can't find then, you can download them from the Samba site:
http://www.samba.org/samba/docs/Samba3-ByExample.pdf
http://www.samba.org/samba/docs/Samb...Collection.pdf
The Samba 3 by Example book have a couple case studies giving detailed solutions for that particular example. It isn't a LDAP how-to however. You might try using google and downloading one of the IBM Red Books for example.