Send yourself reminders via SMS.

Wouldn’t it be convenient if your phone could remind you about important dates, events you need to remember, and things you need to do on your way home from work?

With SMS reminders, you can easily use your phone as a memory aid. And it’s far easier than trying to figure out your phone’s calendar application to set yourself an alarm (or — worse — trying to sync your phone with your computer-based calendar).

The trick is finding a service that will send reminders to your phone. I know of at least three easy alternatives.

If you’re already using an online calendar like Yahoo Calendar or Google Calendar, SMS reminders are already built in to the calendar. All you need to do is select the right option. And if you’re not using one of these calendars, Backpack has a terrific SMS reminder service that’s also free.

With both calendar services you’ll need to confirm your phone number and carrier before you can use the SMS reminder service. They’ll send a test message to your phone containing a secret code, and once you enter this code on the site, you’re good to go.

With Yahoo Calendar, when you create a new event, look for the “Reminders” section about two thirds of the way down the new event form. In that section, you tell Yahoo when to send reminders (it can send you two — for instance, one message two days before the event, and one 15 minutes before it starts) and where to send them: your Yahoo Messenger account, your email address, or your mobile device.

At the specified times, Yahoo will fire off a text message to you, letting you know what’s coming up.

In Google Calendar, you can only select one reminder (but you can tell Google how far in advance of your event that you want it to start). Look for the “Reminder” option in the “Options” section of the “Create Event” form on Google Calendar. It’s just a simple select box. To set up where you want to receive reminders, you need to go to Settings and then click on the Notifications tab. On that tab, you can tell Google how you want to be notified for various types of events (such as upcoming appointments in your calendar or invitations from other Google Calendar users); one of the options is SMS.

Not using either of these online calendars? Your easiest option is probably the Reminders service built in to Backpack. Backpack is an easy-to-use service for creating web pages, taking notes online, and even maintaining to-do lists. Its simplest version includes the reminders service, and its free. You’ve got to create a new Backpack account if you don’t already have one. Then go to the Settings tab on your Backpack site, enter your mobile phone number and carrier, and tell Backpack that’s how you want to receive reminders. (You can also enter an email address.)

Then, to set a reminder, all you have to do is visit the Reminders tab on your Backpack site. Type the text of the reminder you want and specify a time to be reminded. For instance, you can choose from “Later today” (about 5pm your time), “tomorrow morning,” “in a week,” “in a year,” or at a particular date and time you specify. Then click on the Set Reminder button.

The nice thing about Backpack’s reminders is that reminders are very quick to set up, and you can see all of your pending reminders in a simple list — you don’t have to hunt through your calendar to find them. On the other hand, it is another service to keep track of, so if you’re already using an online calendar, that may be an easier option.