Nanjing's large student and teaching population (foreign and Chinese) manage to create a pretty good nightlife for themselves, especially in a city of this size.
There are numerous "western style" bars dotted about the city but the best ones are around the Universities near Shanghai Lu. The small lane opposite Nandar (Nanjing University) Halls of residence is always a good place to kick the evening off in. Jack's is a popular meeting place and although its pretty small, they do a great sweet and sour chicken and the beer is refreshingly cold. The staff here are extra friendly too, always willing to tell (or show) you where the latest hot spots are in town! The music however leaves a lot to be desired.
Down the road from here is where the city's best music talent can be found in, Blowing in the Wind. The groovy owner of this bizarrely decorated bar has nightly jamming sessions in this spacious and comfortable place and at weekends, guest bands are invited on stage to perform.