My own topics

Using iptables to block ips that spam or attack your server

Check Configuring iptables on CentOS post.

Why should you do that while APF or CSF can do it automatically?
Because APF/CSF could block an important bot testing your server to add to search index. So reviewing every ip would be a daily task!
Ok, so how?
using RHEL4, centos4

Using Google AJAX API to copy google results in array

This is some way you can get Google results as a JavaScript array that you can display on any page, you first need to get your Google API Key then try this code…

Sitemap Creator 0.1 : Create Sitemaps 0.9 valid for Google, Yahoo! and MSN Sitemaps

New Sitemap Creator 0.2a available

Sitemap Creator is a php script making use of the
announced new standard SiteMaps protocol supported by Google, Yahoo and MSN.

Allow bots / spiders / crawlers into your private vbulletin forums

There are some very complicated hacks to add but this one line script to do it.
This should be applied to VB 3.5.4
add these lines to the end of your init.php file located in forumroot\includes\init.php

XUL : open URL with a referrer

This is a small function to use in Firefox extension development which makes use of the referrer parameter sent to loadURI() and addTab() functions