Every year when I put up my new calendars I try to find creative ways to use the old ones from last year. Here are some ideas you might want to try with yours:
Art for Framing: My 2014 Zen Calendar has so many gorgeous black and white images I'm going to frame my favorites and hang them in my book room.
ATCs: The covers of old calendars are a nice weight for artist trading cards; I'd cut out mine and add strips of handwritten or typed words to them. I also wrote haiku on sets of three ATCs made from old calendar covers.
Bookmarks: Cut your calendar pages into 2" X 7" strips (or any size you prefer) and use as bookmarks.
Clip Art: Any pictures or art from your old calendars can be cut out and used for a new art or journaling project.
Coasters: You can laminate squares of your calendar to make pretty coasters, or cut up and set out a stack of them as disposables.
Decorative Envelopes: Any paper can be turned into an envelope; take apart an old envelope by the seams and trace it on your old calendar, then cut out, fold and glue stick the seams.
Gift Wrapping: Calendar pages make great wrapping paper for small gifts, too.
Journal pages: If you make your own journals you can cut down old calendars to use as pages; sections of unused day grids from the months work great in handmade planners.
Place Mats: As with the coaster version you can laminate full pages from your calendar to make place mats, or use the pages as disposables.
Check with your local public schools to see if their art teachers will take your old calendars for their students' art projects; just make sure your calendar is age-appropriate and doesn't have any objectionable content or notations on it.
Finally if you have a calendar you forgot to use in 2014, and you don't mind hanging onto it, you can use it again in the future. Any 2014 calendar will also be correct for the years 2025, 2031, 2042, 2053, 2059, 2070, 2081, 2087, 2098, and 2110 -- all you have to do is put the new year on it. If you happen to have any unused calendars from 2009, 1998, 1987, 1981, 1970, 1959, 1953, 1942, 1931, and 1925, these would be correct to resuse for 2015. To find out when any old calendar can be used again, check out this helpful web site.