Control 98
Manage aircraft, panels, sounds, and forcefeed joystick. Still freeware!

Final Approach
Over 4,000 approach charts available with this utility. (From Final Approach)

FSASM
If you need FSASM or related files, get them while the "gettin's good." This site may expire soon.

GaugeDump
Download the ".exe" file. A useful utility for FS98 panel designers. (Shareware)

GPS98
GPS98 for Flight Simulator 98-" The easiest way to navigate without losing your way. (from David Drouin) (Shareware)

Official ADE Page
"ADE (Aircraft Dynamics Editor) is the freeware Aircraft Dynamics and Design Editor for Microsoft Flight Simulator 98 and prior versions. "

Pro-Controller/SquawkBox
How about Real Time Air Traffic Control for FS6? Adds realism to the flight. (from Pro Controller)

Real Weather for FS Pilots
Download real weather for MSFS-95/98 as well as the freeware software required for importing it. (Data from Univ. of Illinois)