Here comes the super classical exercise on recursion along with some variations. If you have any other nice variations, please submit them. At some point, someone should also probably contribute these variations to wikipedia, as only the base problem is nicely described there.
The Interleaved and Split variations come from the following article: "Exploring Recursion with Variations on the Towers of Hanoi", Daniel W. Palmer. Available at http://www.ccscjournal.willmitchell.info/Vol12-96/No2a/Daniel%20W%20Palmer.pdf
The Linear Hanoi is briefly discussed in the article presenting the Linear Twin Towers of Hanoi: "The Linear Twin Towers of Hanoi Problem", Steven Minsker (ACM SIGCSE Bulletin Volume 39 Issue 4, December 2007). This article can only be accessed through the paywall of the editor, sorry.
The 3-colors Towers of Hanoi problem was presented on this web page: http://www.cut-the-knot.org/recurrence/TricolorHanoiAuto.shtml
The Cyclic Towers of Hanoi was proposed by M.D. Atkinson in an article of 1981 titled "The cyclic towers of Hanoi" (Information Processing Letters, Volume 13:3). The article is available at http://www.cs.otago.ac.nz/staffpriv/mike/Papers/Hanoi/CyclicHanoi.pdf.