I chose to write a hugely boring open source product that no one in their right mind would bother with. Old tech, competing with a ton of other similar projects. I focused on the documentation, make it as simple as 'cut and paste this code to get it working' every time someone had a question, bam - a cut and paste example.

Did some serious SEO and soon was racking up a couple of thousand hits a week. This soon hits the million mark. That gets me interviews, even with people who don't want that old tech, they just see results.

I am currently doing a bit of Drupal for a client, there are a TON of half baked modules. Take some of them and make them work. Make them work with the backup module, the restore, the import.... then your CV is padded with a ton of neat stuff.

This is super common advice, the trick is to actually take it. Get all OCD about it and make it work.