For those who are curious...
To figure out what your "junk" silver is worth, you have to basically do math and figure out the weight of the coin (usually stated in grams and convert it to a Troy ounce equivalent) and multiply it times the silver content (stated as a percent), then you can multiply that times the per-ounce bid price to know what the value to buy (before premium) should be and what the ask price to know what the value is to sell (before discount).
Or I can just tell you...
War Nickels - 35% silver - silver content in ounces is 5.635% (actually 5.6352459 if you go out seven places, three should do though)
Pre-1964 Dimes - 90% silver - silver per ounce content is 7.223
Pre-1964 Quarters - 90% silver - 18.084
Bicentennial Quarters - 40% silver - 7.377
Pre-1964 Halves - 90% silver - 36.168
1965-1970 JFK Halves - 40% silver - 14.805
Pre-1935 Dollars - 90% silver - 77.357
1971-1976 Ike Dollars - 40% silver - 31.609
Or, as long as the internets are up you can go to places like this -
http://www.silverrecyclers.com/Calculators/coin_calculator.aspx*But I recommend scribbling the above down somewhere for use in a TEOTWAWKI situation where the internets may no longer be available!