What I'm about to say may sound creepy, but bear with me: I've been practicing lighting, in between shoots, by using foam mannequin heads (the cheap $3 kind, used for sunglasses/head wear displays, found on a major online auctioning site). Got the idea from watching LightFilmSchool.com tutorials.
I do quick 30-45 minute exercises, from time to time, standing one or more heads on cheap light stands and trying different lights/modifiers/moods.
It's not perfect, but it gives you a simple way to evaluate lighting and shadow characteristics of your setups.