Agree with Amarillo and Northern Brewer that have been said so far. Something more resinous like Nugget may be pretty tasty with mate, too. Check out this chart for some good hop descriptions: http://www.byo.com/resources/hops
I'm brewing a batch with Rooibos next weekend, I plan to steep a bunch just after flameout for a few minutes, then turning on the chiller. If the flavor isn't strong after primary, I'll steep more tea in the bottle priming sugar-water.