Fred Miranda seems to be my first port of call when I am researching a lens.

My little 'gem' of a walk-around lens is the Tamron 28-75 (Tamron SP AF 28-75/2.8 XR Di LD Aspherical(IF) Macro lens), as a couple others have mentioned. I LOVE this lens and use it alot for pet/dog portraits and macro stuff.

This butterfly is the first shot I took with the Tamron:



and the puppy I took just a couple days ago:



Hope the pictures post ok as I am not used to embedding images.