You can see what is on Echostar 3 (at 61.5) here:
http://www.lyngsat.com/dig/dish3.shtml
You can see what is on Echostars 1 & 2 (at 148) here:
http://www.lyngsat.com/dig/dish148.shtml
Neither of these show any info on what conditions have to be met to receive the channel (such as subscription package, etc.)
Tony's Dish Channel Chart http://www.dishchannelchart.com/ shows all the channel information in a different format, and includes the info about packages, etc.
Summary: 61.5 includes the following:
3 PPV channels at 470, 471, 472 (duplicated at 148)
1 Dish-on-Demand PPV at 533 (dup'ed at 148)
Promotional and instructional channels (most dup'ed at 148)
various foreign language packages and specific language channels (581-678; most dup'ed at 148)
Soccer and Cricket PPV at 589 (dup'ed at 148)
TV Japan (640) occasionally has programming any Dish subscriber can receive.
Some minor channels in some local markets:
Memphis, TN (1), Detroit (1), Wash., D.C. (5),
NYC (8 ), Pittsburgh (1), Philadelphia (7),
Greenville, SC (3), Orlando, FL (4), Atlanta, GA (2),
Cincinnati, OH (1), Indianapolis, IN (2),
Chicago (5), Cleveland, OH (2), Nashville, TN (2),
St. Louis, MO (2), Tampa, FL (5), Boston (5),
Miami, FL (2), Louisville, KY (1), Buffalo, NY (2),
Ft. Myers, FL (1), Paducah, KY (1), Roanoke, VA (2)
Some Public Interest channels in the 9400-9420 range (most dup'ed on 148)
Some HD channels, now mostly dup'ed on 110. The rest appear to be destined for 105.
Sky Angel, a different DBS service using E* transponders in a convoluted lease/lease-back arrangement, on channels 9701-9781. You would have to subscribe to Sky Angel service.
I have seen statements that ALL locals on 61.5 will be mirrored to 105 and ALL internationals will be mirrored to 121, so it looks like Dish is trying to position themselves to sell E*3 and the 61.5 slots to VOOM.
Lyngsat and the Dish Channel Chart are both highly recommended. The Dish Channel Chart is the same resource mentioned by the previous responder as being at DBStalk. Personally, I prefer the direct link to get there....