I have written (an am maintaining) a fairly extensive presentation on LDAP, OpenLDAP, and integration with various services. I have included a section on back-sql, alot of that section is derived from this excellent document.
ldapv3.pdf (ftp://kalamazoolinux.org/pub/pdf/ldapv3.pdf) hosted by the Kalamazoo Linux Users Group (http://www.kalamazoolinux.org/). (Kalamazoo, Mi. USA)
An open, cross-platform journaling program.
A scientific plotting package.