I've written a modest data binding library for haskell GUIs; the code is at http://code.accursoft.com/binding/. binding-core exposes functionality for binding IO objects to mutable variables and lists. bindnig-gtk and binding-wx are wrappers for Gtk2Hs and WxHaskell respectively. Examples of how to use these can be found in the tests directory of binding-core, and the demo directories of the GUI wrappers. Thank you!