Recreational Mathematics Colloquium mentioned in the comments above : http://ludicum.org/ev/rm/13
A mixed bag of (possibly) relevant journals, some of them well-known:
- Convergence
- Forum Geometricorum
- Mathematical Intelligencer
- Mathematics Magazine: MAA JSTOR
- Plus
EDIT
And more, including a French one:
- The Mathematical Gazette (UK).
- l'Ouvert (not sure about its current status, the site appears not uptodate and somewhat broken)