The Nielsen organization has presented the ratings for the season for every show on broadcast television, which shows the top programs for each network. You can find the complete list of all programs here.
The lists include the top five and bottom two shows on each network for the 2011-12 season, along with their total Nielsen rankings in total viewers (including sports pre- and post-game shows, but not game telecasts or summer shows like America's Got Talent). Also included are the top shows among the adults 18-49 demogrpahic. While DVR ratings may change the numbers some, it probably won't change the rankings.
ABC
1. Dancing With the Stars performance show, 18.33 million viewers (5th overall)
2. Dancing With the Stars results, 16.08 million (6th)
3. Modern Family, 12.93 million (17th)
4. Castle, 12.18 million (22nd)
5. Once Upon a Time, 11.71 million (28th)
Top 5 in adults 18-49: Modern Family (5.5 rating, tied for 5th overall); Grey's Anatomy (4.2, 12th); Once Upon a Time (4.1, t-17th); Desperate Housewives (3.6, t-26th); Dancing With the Stars performance show (3.4, t-30th)
Bottom 2: Saturday Movie of the Week 3.46 million viewers (156th) and You Deserve It, 4.81 million (126th)
CBS
1. NCIS, 19.49 million (3rd)
2. NCIS: Los Angeles, 16.01 million (7th)
3. The Big Bang Theory 15.82 million (8th)
4. Two and a Half Men 14.64 million (11th)
5. The Mentalist 14.57 million (12th)
Top 5 in adults 18-49: The Big Bang Theory (5.5, t-5th); Two and a Half Men (5.1, 9th); 2 Broke Girls (4.4, t-10th); How I Met Your Mother (4.1, t-17th); NCIS and Survivor: South Pacific (4.0, t-19th)
Bottom 2: 48 Hours Mystery, 5.82 million (102nd) and A Gifted Man, 8.63 million (60th)
FOX
1. American Idol Wednesday, 19.81 million (2nd)
2. American Idol Thursday, 18.33 million (4th)
3. The X Factor Wednesday, 12.67 million (19th)
4. The X Factor Thursday, 12.57 million (20th)
5. Terra Nova, 10.08 million (43rd)
Top 5 in adults 18-49: American Idol Wednesday (6.2, 2nd); American Idol Thursday (5.5, t-5th); The X Factor Wednesday (4.4, t-10th); New Girl (4.2, t-14th); The X Factor Thursday (4.2, t-14th)
Bottom 2: Q'Viva! The Chosen (1.88 million, 179th) and Breaking In (3.45 million, 157th)
NBC
1. Sunday Night Football, 20.74 million* (1st)
2. The Voice (15.77 million, 9th)
3. The Voice results show (10.92 million, 35th)
4. Smash (8.94 million, 51st)
5. Harry's Law (8.92 million, 52nd)
*Includes broadcasts only from the start of the Nielsen season on Sept. 19. Including games aired prior to that, SNF's season average is 21.25 million viewers and 8.3 in adults 18-49.
Top 5 in adults 18-49: Sunday Night Football (8.0, 1st); The Voice (6.1, 3rd); The Voice results show (4.2, t-15th); The Office (3.4, t-30th); Smash (3.2, t-43rd)
Bottom 2: Escape Routes (1.11 million, 192nd) and Bent 9:30 p.m. (3.05 million, 164th)
The CW
1. The Vampire Diaries, 2.78 million (166th)
2. America's Next Top Model All-stars, 2.42 million (172nd)
3. The Secret Circle, 2.06 million (175th)
4. Supernatural, 2.03 million (176th)
5. One Tree Hill, 1.86 million (180th)
Top 5 in adults 18-49: The Vampire Diaries (1.3, t-137th); America's Next Top Model All-Stars (1.1, t-148th); One Tree Hill (1.0, t-157th); The Secret Circle (0.9, t-163rd); Supernatural (0.9, t-163rd)
Bottom 2: The L.A. Complex (572,000, 195th and last on the five English-language nets) and Remodeled (711,000, 194th)
Zap2It
I've noticed a few of these top 5 shows have been cancelled, so certainly interesting to see some of them were actually well watched (Terra Nova, Secret Circle for example).