Om Namo Bhagavate Vasudevaya
I learned this chant while at my Yoga Teacher Training at Kripalu. It roughly translates to "O my Lord, the all-pervading Personality of Godhead, I offer my respectful obeisances unto you".
Om Gum Ganapatayei Namaha
I learned this chant from my boyfriend Forrest. Chanted to Ganesha, it roughly translates to "Salutations to the Remover of Obstacles".
Baba Nam Kevalam
I just learned this chant last Tuesday during Spirituality Club at Green Mountain College. It roughly translates to "Love is all you need" or "Love is the essence of all things". (Says it all, right?!)
If you've been having trouble focusing during your meditation practice, maybe you could try a chant next time.
Jai!