Ajax and the Jewish connection
Its not really a recent thing that they have been selling Star of David's outside the ground. The old ground was built in a Jewish area and the connection developed from there. The players in the 70's were very emersed in the Jewish culture, using Yiddish pharses and such.
When they were drawn against an Isreali team in the European or Uefa Cup the F-side were given a special welcome by the Isreali's (one of the Isreali papers went as far as to call the match a Jewish derby)
However some Jewish fans who go and watch Ajax are a bit embrassed by the behaviour of the F-side and point out the club aren't really Jewish. (info from David Winner's excelent 'Brilliant Orange'