I am shooting with the D90 and 18-105 primarily. I have a home studio setup with an SB900 and SB700 and use the SU800 wireless commander. My problem is that all of the photos look properly exposed on the LCD but are quite a bit unexposed when I upload them. I realize the LCD is not going to give a perfect preview, but the difference is so great that the photos are almost unusable. I upped the flash exposure compensation on both units which helped, but maybe there is something I am missing? I also took some in raw, which I figured would give me greater latitude, but I couldn't even get those to look right.
I am taking pictures of guitars, I can upload some if you want to see....
EDIT: Here are some samples. The first sunburst guitar is okay, but still at least 1 stop darker than it looked on my LCD. The second of the blonde guitar looked fine on the LCD. In fact, I could see all the detail around the headstock and the tuning machines were easily distinguished from the background. I am not sure why this is happening but I don't think it's user error. I never noticed this kind of difference before and have been shooting with the D90 for two years now.
Also, I think there is a firmware update. Maybe I should try that?? Thanks! Any help is appreciated.