F.lux: This little guy minimizes blue light exposure by applying a funky orange glow on your computer screen which automatically fades in with the sunset time of your region. This is great for when you need to work late at night as it minimizes the disruption of our natural circadium rhythm. This is actually something I want to get installed in university computer rooms for students working late at night.
Unroll.me: Unroll.me allows you to see how many email newsletters you're subscribed to (scary!) and then gives you the option of unsubscribing from them, keeping them in your inbox or adding them to what they call a Rollup - a single email containing multiple newsletters. No more crowded inbox!
Boomerang for Gmail: On the topic of emails, Boomerang is another tool I love. It allows you to schedule email sending, return messages to your inbox at a later time to allow you to focus on more important work and much more, all from within your current Gmail.
Dropbox, Pocket, Delicious: Some tools I use to save content on one device and access it on all others. Pocket is without doubt my top choice here. Rather than allowing myself to get distracted by new articles and research, I simply use the Pocket browser extension to save them for reading later. The cool part is it allows you to read offline and creates a very minimalist reading experience, removing all ads and distractions.
IFTTT: These guys are wizards. IFTTT stands for If "This Then That" and allows you to create "recipes" which automatically play out when a trigger is activated. For example, you can set a recipe which automatically updates your Twitter profile pic when you change your Facebook profile pic. This is a tiny example, but the possibilities are endless! Give it a go.
LastPass: LastPass saves all your current passwords (as well as other sensitive information you want to save) into a vault and then requires you to only remember one master password. When filling in a login form, you can simply recall your passwords using the master password. There is also the option to generate random passwords which are stronger than those you would pick yourself.
Trello: It took me a while to start using, but Trello has been a game changer in terms of organising projects and increasing my productivity. Check it out.
FastKeys: OK, if you're using Windows, you simply need to get this tool - it is hands down the best $10 I have ever spent. FastKeys allows you to create keyboard shortcuts to launch scripts, programs, files, etc. and also allows you to launch several programs at once with the click of a button. My description doesn't do it any justice. Just get it and thank me later!