Tibetan rosaries, called mala, are used to count the number of times a mantra is repeated. If no mantra chanting is involved, they cannot help with timing. Some meditators rely on incense that burns at a consistent rate, usually one stick will last +/-20 minutes. For this try Japanese incense that is non-dipped, meaning there is no stick. I prefer Tibetan incense, which can be pretty powerful and earthy and help induce a meditative state (but I don't time my sessions with it). Of course timing with incense works better with open-eyed meditation, or with tasks. (Though more challenging, meditating with the eyes open is more powerful in my opinion, once it is learned.) Another interesting option that'd I'd like to try, but is costly, are the Zen Alarm Clocks. There are several varieties, but all involve actual tuned chimes. They can be set as countdown or interval timers, or as regular alarm clocks. The most interesting feature of these is a setting in which the chime strikes become more frequent over a ten minute period followint the "golden ratio". Better than the fixed snooze button, I would think. If anyone has any questions about meditating, I'd be happy to share what I've learned.