For hacking WebDriver without real production purpose, you need to find some task that really motivates you.
Don’t forget, WebDriver – is not only about test automation, people use the tool (not so widely) for many different purposes: crawling some data from websites, semi-automating real job-related tasks.
For instance, a girlfriend of friend of mine is working for real-estate agency. The part of her job was to update actual ads. She has to find all ads belong to her account, and re-save each on multiple different web-sites.
My friend wrote a Console application with C# and WebDriver which automates those actions:
Login to website
For each page in the account:
Open and resave each ad on the page.
When I mentoring new person whom is willing to learn test automation, I give him/her a task to write a program which gathers the trains information (availability and ticket prize) on the Ukrainian Railways website.
They have really tricky undocumented prizing; which depends on the days of the week and the amount of time before the departure.
The program should log information about all available trains on the time when it started.
An Airlines Company website is also a good option. You can try this one. It is complicated enough:
And you can also write a console application which sends new messages to twitter. Of course, it should support image attachments. That could be a good candidate to post on Hacker News.
I haven’t heard someone had done something like that before.