Depends on your definition of "mega corporately owned"...I will assume that you wouls consider a relatively small owner like Lincoln Financial (WSTR Star 94) to be a "mega corporation" due to their large business overall, or the Dickey brothers (WCNN 680 The Fan, WALR 1340, WFOM 1230) due to their Cumulus holdings and management.
On the FM dial (all of these signals would be considered rimshots at best, and I am sure that I have missed several)
WEKS 92.5 The Bear--Locally O&O
WVFJ J93.3--How many stations does Provident own? See the recent thread about them.
WCON 99.3--Locally O&O
WNSY La Raza 100.1--Owned by Davis Media out of Columbus.
WLKQ La Raza 102.3--Ditto. WNSY and WLKQ simulcast.
WMJE Majic 102.9--Locally O&O (Jacobs Media)
WTSH South 107.1--Owned by Southern Broadcasting; probably up for sale soon as Southern seems to be getting out of the biz. Currently being LMAed by a Rome-based group that recently MBOed some of Southern's other Rome cluster stations. Southern recently sold their Athens cluster to Cox. WTSH currently has a CP to up their power and cover more of the metro area.
On the AM dial there is a plethora of small, locally owned stations. Stations of note with decent-size signals:
WDUN 550--sister to WMJE.
WAEC 860 (Love 86)--Not sure how big the ownership group is.
WGUN 1010--Locally O&O with a 50k day signal.
WCFO 1160--Locally O&O (Jack Weber).
WMLB 1690--sister to WCFO.