I've had some luck with my phone actually. I don't wear a watch so I check my phone fairly often for the time. This can work well as most people have their cell phones on them 24/7. When I'm dreaming if I try to check my phone it won't turn on, the screen will be messed up but usually I just get a black screen and a phone that wont turn on - which lets me know I'm dreaming.

Another thing is digital clocks - everytime you see one force yourself to do a quick RC: (I know this is a common thing most people know but I do it a little differently) Check the time on a digital clock, and stare at it for about ten seconds. Sometimes when I'm dreaming after a few seconds the numbers will just start randomly changing. If they don't change, note the time and look away, then look back after a few seconds. If the time changed by more than one minute you're probably dreaming. Even if it only changed by a minute - which could easily happen in reality - perform the same check again and see if it changes further.

Lastly, most people (including myself) have difficulty reading text in dreams. Sometimes, for me, this manifests itself as me physically not being able to turn my head towards text, seeing jumbled words and letters, words not making sense, or just seeing a garbled grey blurry mess. So when you can read text (such as this) remind yourself that you're likely not dreaming because you can read it. This can be deceptive though because sometimes I can read substantial amounts of text in my dreams - it just normally doesn't make any sense.

Good luck!