"However, due to an anomaly of the html, pasting the abc's into the concertina.net converter results in double-spacing. For concertina.net's conversion program to work you must remove the spaces between all the lines of abc notation after pasting, so that they are single-spaced, with no intervening blank lines. This being done, the F/C abc's will convert to standard notation nicely."
There is also a nice conversion program at www.folkinfo.org although this suffers from the same problem as concertina.net on the Fiddler's companion tunes.