I have a rain jacket I bought for hiking made of Gore-tex Paclite that is lightweight, very packable, and waterproof. It was pretty pricey though has been totally worth it to me, and I'll have it for a long time. It's made by Outdoor Research. I would definitely recommend Gore-tex Paclite, though I bought this jacket about 4 years ago now, so there may be something even higher-tech/better now in rain gear. At the time, it was top of the line.
Emily
2011 Jamis Dakar XC "Toto" - Selle Italia Ldy Gel Flow
2007 Trek Pilot 5.0 WSD "Gloria" - Selle Italia Diva Gel Flow
2004 Bike Friday Petite Pocket Crusoe - Selle Italia Diva Gel Flow