My life revolves around my task-management list. As a student, a writer, a blogger, and just a person, there are a number of different things I have going on. I spent a long time looking for the perfect tool to manage all the things I had to do, but I never thought I’d find it.

Then I did. It’s called Remember the Milk.

Remember the Milk (RTM) is the most fully-featured task manager out there, and is starting to succeed enormously because of it. There are countless reasons for why it’s so great, but here are my top 15:

(Disclaimer: though most of RTM is free, and is by far the best task manager even free, some features require a pro account, which is $25/year. It’s one of the few apps I’ve ever paid for, and it’s a total steal. I’ll let you know which are pro-only features.)

1. It’s Free. I tried using several other apps before RTM, like Backpack and Nozbe, but both of those were crippled without paying for them. Though paying for RTM opens up new features, you can do a massive number of things with the free version. Without paying a dime, it’s still the best task manager out there.

2. It’s Simple to Use. Right out of the box, you can figure out how to use RTM. Adding tasks, lists, tags and due dates is incredibly intuitive. Whether you want one list or 100, sorted by due date, tag or priority, you can do it with little or no learning curve. If you do want a little help, RTM offers some basic instructions here and here.

3. You can use it offline. Google Gears is a product that’s gaining in both popularity and usefulness. Basically, the way it works is to synchronize your usage, so that you can continue to use the apps seamlessly going on and offline. RTM is one of the first, and best, implementations of Gears into a non-Google application. Using Gears, as long as your browser is open you can always access your tasks, whether you’re online or off. One of the biggest things people don’t like about online task apps is that they require being online- not so with RTM. Gears is available for Windows, Windows Mobile, Mac (Firefox and Safari), Linux and Android.

4. It’s as customizable as you want it to be. Similarly to #2, you can use RTM right out of the box. If you want, you can start adding things like locations, smart lists, tags, shared tasks, and so on. It can be as involved and complex as you want it to be, or as simple as possible.

5. It has keyboardy goodness. I tried something, and I was right. You can do nearly everything in RTM without ever touching your mouse. Keyboard shortcuts abound, and once you’ve learned them you’ll be flying through your tasks like nobody’s business. For a full list of the keyboard shortcuts, go here.

6. It works with email. Most people spend their lives within their email. RTM gives every account an email address, and by simply sending an email to your RTM account, you can add tasks. You can even specify in the email, the due dates, tags, and all the other data related to the tasks that you want. A suggestion? Set up a template that you fill in, based on the RTM page here.

7. It works with Gmail. If you use Firefox, the RTM for Gmail extension (here) is one of the best out there. It integrates beautifully with Gmail, letting you manage all your tasks right from the Gmail screen. It’s a step closer to being like Outlook, and is a perfect place to manage life for someone who’s addicted to email. If you don’t have Firefox, RTM just released a gadget for Gmail (here) that puts your tasks right into the Gmail sidebar. It’s not as full-featured as the Firefox extension, but it does the job in any browser.

8. Gadgets, gadgets, gadgets. One of my favorite things about RTM is that there are a ton of ways to interact with it that don’t require being on the RTM site. Twitter, Jott, Google Calendar, iGoogle and NetVibes can all be used to interact with RTM. For an almost full list, check out RTM’s “Services” page here.

9. Mobile Prettiness. For any cell phone you’re using, the RTM mobile link (m.rememberthemilk.com) brings a very nice, very usable interface. No matter where you are or what you’re using, RTM is designed to work well as long as you’ve got a browser. If you’ve got an iPhone (pro only), the link is i.rememberthemilk.com, and is the same gorgeous interface. If you’re not pro on the iPhone, the regular mobile link gets the job done.

10. Synchronize, synchronize, synchronize. (pro only) Got an iPhone? How about a Blackberry? A Windows Mobile phone? Then say hello to MilkSync (here), the ingenious sync system from RTM. Instead of putting a whole new application on your device, it syncs directly (and well) with your native tasks application. On occasion, you might lose a bit of data in the sync, but it works really well syncing between the native device list and the RTM Web happiness.

11. It knows where you’re going. This is a feature that I don’t make nearly enough use of. If you’re an errand runner, and are constantly out, this is the clincher feature. You can input certain locations (the mall, your house, school, office, etc.), and then assign locations to each task. Then, at any given time, have a look and see what tasks can be done near where you currently are. You can put addresses in (for your own use, also), and then make sure you get everything done near wherever you are. My favorite feature? Go to the “Locations” section, and find out where your tasks are. Great way to schedule your day.

12. Set reminders- or don’t. Want a reminder on your cell phone? 30 minutes before a task is due? How about a once-a-day digest in your email? Check, check, and check. Set reminders for all or none of your tasks, to IM clients, email, Twitter, or cell phone.

13. Print it out. If you’re an offline kind of guy, you can print out a “Weekly Planner” of all your upcoming tasks. It’s an attractive, easy to use paper-based task manager. Check off tasks, and then at the end of the week go back and enter the results back into RTM. It’s a nice feature to make transitioning from paper-based to Web-based easier on you.

14. Its lists are as smart as you are. With the “Smart List” feature, you can create task lists based on when they’re due, where they are, how long they’ll take, what tags they have, and anything else you can think of. Me? I have three- one is overdue tasks plus ones due in the next seven days; one is all my tasks (for quick looking over); and one is tasks with no due date (to check once in a while to make sure I don’t forget). The searching is incredibly advanced, and lists can be made with any of the options here.

15. Bob. How can you not love this monkey? I’m sold right there.

Want to get started Remembering the Milk? Check it out here.

Update: It’s quite the RTM day for me- I have a new post on Gearfire today, in which I give a shout out to RTM. Check it out here.

Do you use RTM? Why? If not, why not? What features do you want in a killer task management app? Let us know in the comments.