Here's a partial list, primarily of nighttime signals...
990-WRFM Muncie, IN -- 1 watt, 6 towers
1190-KQQZ Desoto, MO -- 22 watts, 5 towers
1440-WRGM Ontario, OH -- 28 watts, 6 towers
910-KINA Salina, KS -- 29 watts, 5 towers
1330-WKTA Evanston, IL -- 110 watts, 6 towers
850-KEYH Houston, TX -- 185 watts, 5 towers
1380-KMUS Sperry, OK -- 250 watts, 6 towers
1520-WNWT Rossford, OH -- 400 watts, 5 towers
500 watts, 6 towers:
1090-KMXA Aurora, CO
1090-WCAR Livonia, MI
1150-WCUE Cuyahoga Falls, OH
1520-KFXZ Lafayette, LA
1600-WHIY Huntsville, AL
500 watts, 5 towers:
620-WAKY Louisville, KY
970-KNIH Paradise, NV
890-KJME Fountain, CO -- 580 watts, 6 towers
780-KCEG Fountain, CO -- 720 watts, 6 towers
580-WKTY La Crosse, WI -- 740 watts, 5 towers
1430-WEEF Deerfield, IL -- 750 watts, 6 towers
820-WVSG Columbus, OH -- 790 watts, 6 towers
1520-KOLM Rochester, MN -- 800 watts, 6 towers
700-KHSE Wylie, TX -- 920 watts, 6 towers
740-KVOX Fargo, ND -- 940 watts, 6 towers
1020-WURN Kendall, FL -- 980 watts, 6 towers
1000 watts, 6 towers:
670-WWFE Miami, FL
790-WSGW Saginaw, MI
1070-KHMO Hannibal, MO
1160-KVCE Highland Park, TX
1170-KBOB Davenport, IA
1440-WMKM Inkster, MI
1470-WVOL Berry Hill, TN
1520-WMLM St. Louis, MI
1540-KEDA San Antonio, TX
1000 watts, 5 towers:
560-WHBQ Memphis, TN
650-WNMT Nashwauk, MN
710-KFIA Carmichael, CA
1030-WCTS Maplewood, MN
1070-WKOK Sunbury, PA
1270-WHLD Niagara Falls, NY
I haven't checked the daytime listings. I think radio-timetraveller (Bill) has a program he can use to find things like this quickly.

I found a list he had given me of signal strengths at my location, which included all nighttime skywave US & Canada signals as of 9-14-2014. The daytime signals only included 5 µV/m and higher groundwave signals, though, which eliminates many of the AM stations across the USA. I imported it into LibreOffice Calc, eliminated all stations outside the scope of the OP (over 1 kW, fewer than 5 towers), then looked up the facility IDs on the FCC to make any necessary callsign updates.