Dmitry We could use this discussion topic to complete that list then! Everyone is welcome to share their favourite hacks. I'll start:
I'm not sure anyone mentioned Evernote in the masterlist, so I'll go ahead and do it. I find it really useful because of its e-mail inbox integration, which allows me to turn emails into to-do tasks in no time, and because it's really simple to save articles, websites, ecc. to check out later with the Chrome extension as well.
As regards social media management I can recommend ManageFlitter, which is a great tool to manage your Twitter account: you can schedule your tweets, manage your followers and obtain precious info about them, obtain suggested content to show to your followers as well as suggestions to enhance your presence on Twitter, and the Pro Account offers even more features.