We do quite a bit of software development at AADL, and some of the work we've done may be of interest or use to other libraries. Our website is powered by the completely awesome open-source CMS Drupal, and much of our development takes the form of drupal modules. We also run Innovative Millennium (Triple-I), so many of our drupal modules use shared code libraries or PHP classes that we've developed to interface with our III server. Here are several tools you may be interested in, especially if you've got PHP experience or are running III.
One of the things lacking from III is a way to easily update/change/add MARC fields that have unique values. An editing interface does exist in the terminal interface for records which this PHP class wraps around to provide a programmatic interface.
The III web opac comes stock with a plain text dump of patron data based on a key. This PHP class provides a wrapper around this page import the data into an easy to use array.