If you are a heavy twitter use, possibly with more then one account, than I suggest you to give Tweetdeck a try. You can arrange, schedule, monitor and manage your tweets with ease.
If there is a vast number of unimportant unread emails accumulating your Gmail inbox and it's starting to bother you, but you don't have time or nerves to mark them as read page by page, this is what you can do.
If you want to start learning PHP and MySql, the first step is to setup complete environment on your local computer. This will include Apache web server with PHP support and MySql database server.
With the new version of Photoshop, you also get a new cropping tool called Perspective Crop Tool which will change the perspective on a image. Check it out, it really is a cool tool.
You will learn how to install a Google Analytics plug-in to your Wordpress site and connect it to a Google Analytics account, so you can start tracking your web traffic.