MSR Hubba Hubba Fast & Light Tent
This is a great, lightweight three-season tent that you will love. You can set it up with just the fly and footprint if you just need shelter and want to save weight. Winner of Backpacker magazine's Editor's Choice. This tent is big enough for two people (or you and your dog). There's also a Hubba, which is really the same tent sized for one person. (http://www.rockcreek.com/products/listing/item7775.asp)
This is a great lightweight 3-season backpacking tent. With only 1 pole and some clips, it's fast to set up so you don't have to worry if there is an approaching storm. You can even leave the tent body at home to save weight and set it up as a canopy in the summer.