A few years ago, I made a web script I could use to get a random reminder to do a reality check. The reminders were arranged in categories:
You'd refresh the page, and get a random tip, sign, to-do, or action.
It was also intended to be a deck of cards, eventually, and that still may happen.
But for now, the old "dreamcards" script lives on here. I've created an iphone app, too. Now when you're just hanging around being bored, you can lucidify your life a little and do a reality check. The app is free and ad-supported (many of the ads will be for lucid dreaming related products, so you may actually want to see them!)
For a dollar, you can upgrade to the ad-free version that can also send you periodic reminders so you can do reality checks when you're not thinking about it.
For notifications, you can choose between a few sounds. You should try to select one that's distinctive, that you like, and that you will come to recognize. Then, sleep with your iphone near you; when the reminder comes through, you should be able to recognize the sound and do the reality check in your dream.