Hi,
I'm Joost de Valk, aka Yoast.
I have developed many a WordPress plugin. The two most popular ones are:
There are more plugins, you can find them on my WordPress plugins page. If there's anything else you want to know about me, or if you want to read my blog which has a lot of posts about WordPress, SEO and Analytics, go to yoast.com.
All the best,
Joost