Low tower height notwithstanding, WOMC still really gets out. That's why it's so hard for me to understand why I can almost never get them in HD in the Ann Arbor area. I have an easier time getting an HD signal from the much weaker Mix 92.3 than I do from WOMC.
Another public station that seems to really get out is WCMU 89.5 in Mount Pleasant. Until the Smile FM 89.5 in Riverview signed on, they boomed into the Ann Arbor area frequently, especially in the summer months. Along with some of the other Tri-Cities powerhouses like WHNN, WIOG and WUGN, they are one of the few FMs I can hear both this far south and up north in Gaylord.
Forgot to mention also WRKR 107.7 Portage/Kalamazoo. When I lived in Saline, I often could get them like a local even during dead-band conditions. That ended when the 107.7 in North Baltimore, OH moved to Luckey. Still, I can get them pretty easily in the St. Johns area north of Lansing.
On the AM side, I also give a mention to WMIC 660 out of Sandusky. Due to their low dial position and despite being daytime-only, they can be heard listenably from the metro Detroit area to Alpena and even as far west as Lansing.
Speaking of WKAR, its AM signal doesn't do too badly either in terms of coverage, although it did a lot better before it adopted IBOC. Which has also rendered it nearly unlistenable, even if you can pick it up, because of the annoying "buzz" sound. Also from Lansing, 730 WVFN, 1180 WXLA and 1320 WILS have pretty darn powerful northbound signals during the day... nighttime is a different story (of course WXLA is a daytimer).
As far as coverage "wimps"... pretty much any AM station in northern lower Michigan with the possible exception of 580 WTCM (which has 50,000 watts on a low dial position in its favor) would count, due to the poor soil conductivity. Worst of all would probably be 1210 WJNL. 50,000 watts with a coverage area equivalent to 250 watts... or so it seems. It's a chore to get them to stop the Scan/Seek on a car radio in Traverse City, which is in their county of license!