A long while back, I endorsed naturally decaffeinated rooibos tea in all sorts of flavors as a fantastic late night "snack": www.sparkpeople.com/mypa
However, I'm also a super fan of all kinds of tea as mid-day snacks. My favorites are: cream earl grey (black), jasmine green tea, milk/ginseng oolong, rose black tea, assam TGFOP (black), and Matcha Sencha (super green).
These are all fantastically flavorful teas that don't require milk or sugar, they just require that you *only* steep them for 3-4 minutes. Not overbrewing your tea is really the trick to the tastiest of drinks. If you get into the habit, tea is also a great way to consume all your daily water. And if you reuse tea leaves (only adding a pinch of new leaves on rebrewing), you can minimize the caffeine intake as well...without going through your whole tea stash on a daily basis.
If you don't live near a loose leaf tea shop, I really like Adagio Teas. Lots of variety, an effort towards fair trade, and reasonable shipping costs.
One tea that's really worth a second look, especially if you like Starbuck's green tea lattes, is a Matcha Sencha tea that you can get at an Asian/Japanese grocery store. The first cup, you just pour the hot water over the leaves, no steeping! This will give you a perfectly vegetal tasting cup of matcha. The second time, you steep the leaves ~3mins and you get a nice cup of sencha tea! 'Just a little variety without any of the effort.
I drank many cups of Matcha iri Sencha when I was in Japan. It's supposed to help you lose weight, and I [accidentally] lost tons of weight in Japan, but maybe it was just from all the water consumption?
P.S. SparkPeople recently posted an article on the benefits of matcha, and Matcha iri Sencha might be one easy way to get into it: www.sparkpeople.com/reso
P.P.S. Costco also sells this matcha green tea: www.costco.com/Kirkland-