Nowadays a lot of websites provide the service of integrating their software in your site, plugins/extensions/widgets to boost the functionality of your own site.
A good example is the meebo me widget: a mini private chat module, that you could easily use as chat-support. Every pagevisitor starts a private conversation with you, the site-owner, the meebo-account-holder.
You don't always need to pay for software. Often programs are available as freeware or as free source code, in which case you could also customize, downgrade, upgrade it to suit your needs.
Building for example your own user friendly (site) content management system (CMS) can easily take several months. Open source can here come to the rescue: you only need to style the templates to match the desired look instead of building the complete templating system. If you want more than the basics, customization is needed, which in turn can also take several months... A difficult choice for the both of us.
A lot of open source projects are listed on sourceforge.net, but the easiest way is ofcuz to add the term "open source" to your search string, e.g. "cms open source" or "blog open source".
FREE TIP & FREE OFFICEFor the computer user:A collection of freeware, because available as open source, software for your every day need can be found @ theOpenCD.org, e.g. the openOffice suite