I'm not 100% sure, but many CFS2 objects by third parties are object libraries and can be placed in FS9. The default vehicles, weapons, etc are definitely libraries and I'm sure I've used some in the past. For 3rd party stuff, trawl the CFS2 addons in the library and archives, take note of anything from pen32win & AF stuff, Wolfi, Maskrider (and associated libraries), XavierB, and others (sorry guys if I missed you out!).
I've certainly used some of pens stuff before, camo nets and revetments, etc.
Jamie.
PS. a note of caution, not all are libraries and will not work, I suggest making a 'test' scenery folder and testing them one at a time before moving them in permanently.