Ho sempre cercato icone di questo tipo e smashing magazine risponde prontamente alle richieste di supporto:

Designer’s attention to small details often has a significant impact on how visitors perceive the overall design of a web-site. Although users’ main focus usually lies on finding information, it’s nice to find the content being supported by finest visual details. This holds for favicons, shopping carts, pagination and tag clouds we’ve covered in our earlier posts. But it also holds for… well, date stamps and calendars. Apparently, the latter are used not only in weblogs, but also on large web-sites where events, news and any kind of time-planning is involved.

http://www.smashingmagazine.com/