First I chose to develop my own system so I can customize everything as I want... and also because I enjoy coding.
I used the php/mysql couple for the server side coding (nothing unusual, when I 'll have some time I'd like to try Python or Ruby).
I also use the template engine Smarty, since I've been working with it, I love it : plus a MCV framework the code is really clean.
Design (page HTML) on the one side and server coding on the other side, classic and easy to maintain.
As for javascript I like to use Mootools. Google offers to download the Mootools file from their server in your HTML page, a really interesting process that I am testing : the more the developers will use this process, the more it will be usefull.
Basically, If you previously visited a website who used Mootools from Google, the access to my page will be quicker, nice saving of time.
For now, Google offers only the 1.11 version of Mootools but I hope they will quickly host the 1.2.
(To learn more about this, check here : google/ajax/documentation and here : ajaxian.com. All the major javascript libraries are supported).
I also use rewrite_mod to have SEO "friendly" Urls...and mainly cause it looks better and easy to use.
As you can see on the top right of the page, this blog supports 3 languages. Clicking on a flag redirects you to the same page translated and not to the top page which is nice I think.
As for the comments avatars, I use some flickr photos under Creative Commons License. When you add a comment and choose an avatar, a link appears. This link redirects you to the photo's author.
I also use a Creative Commons License for the blog itself(link at the bottom of the page).
To fight any spammers I use a class from the Zend Framework to connect to the API of Akismet... will see if it works!
The navigation in this site is really "ultra not unusual"! : the 4 main categories are reachable by the photos in the top menu, and a tag cloud.
Plus, some links "previous articles" or "related articles" will be here and there.
The site is minimalist; I like it like that, I will add other functions later but the design will remain simple.
That's it, for those who read until here and undertood nothing, no worry! : I invite you to read my other posts ;)