I was a newbie to PHP, MySQL, and even only the most basic at CSS when I first got wordpress.. But I found making a plugin really helped me understand all the inner workings.
My plugin is fairly simple but I thought I'd post it here as it can be an excellent example for those trying to learn how to make a plugin themselves.
For sites with multiple authors, it can be fun to find out how much of a "share" each author has; how much a percentage of the posting database was written by you.
This plugin went over-the-top and (attempted to) do everything by the book - well documented source code, nicely organized, neatly expandable, complete with an admin interface, a "high-score" table, database-stored variables, and even a function that can be externally called for implementation into themes or whatever. :)
Check out the details at my site: Weasel's AuthorShare Plugin