I added a 55-300mm f/4.5-5.6 lens yesterday. I was intending to get the 55-200mm as I've used it before and was very impressed by the quality. However I decided to try this longer version. Its very good, tremendous value with good stabilisation.
Again the D5100 performed well on a variety of shots. I really do like the colour.
I also shot a video with the 55-300mm. Again superb results. This camera actually makes me want to go out and shoot video, its so good. The colours are just beautiful, and actually really lifelike. Very impressive.