There's not much I can add to the great tips and tricks of the trade that everyone else has put. Definitely communicate with bossie, and don't be afraid to ask to handle specific tasks. That's how I've promoted myself. I saw my supervisor getting snowed under and asked to take over a specific project that I knew I could do (and would also challenge me and offered professional growth) so that she would have more time to handle the issues and projects that I couldn't take over.
On the employees issue... Again talk to bossie. Maybe he doesn't want you "in betwen", maybe he does. Get your guidance from him. If you do act as his eyes and ears for the office/company, then only worry with making him aware of anything that will affect the company or could get back to him in some way (and that his not seeming to know about could make him look bad). I generally would step into bossie's office when he had a slow moment or after work, and tell him that "FYI, just in case, X and Y were at it again. Be prepared for X to show up in your office demanding....". If it is something that has potential to blow up right away, then I'd get a hold of him ASAP to tell him. Most of it is common sense. If you were in his shoes, what would you need to know?
Of course, there is always the faithful crystal ball....
Winkie, aren't you on the committee supplying those to all of our new admins?
CountriGal
Deskdemon Editorial Board Member 
