Nikon SB-600
If you are an occasional flash user that would like to take advantage of Nikon’s CLS system, the SB-600 at around $229 will do the job really well. With this flash you can set any Nikon DSLR (post D100) in ‘receiver’ mode and can be controlled with your pop-up flash for more creative and/or better flash pictures. This flash has a guide number of 98 ft which I do believe it might work really well for most users and most applications. The 600 can be used as a slave flash but not as a master/commander unit.
