Quite many programs need it, actually ..... many HTML editors, Help files (in HTMLhelp format (.chm)), many programs that display HTML in some way ... Also many of the filesharing tools need IE, Morpheus, Kazaa, etc. ... And possibly even some e-mail clients rely on the MSIE engine for displaying HTML mail.
I've had IE free systems until very recently (when I had to install it because I needed to develop HTMLhelp ....) and ran into programs that needed the engine quite often.
Even some browsers!
Good that K-Meleon needs nothing but Win32 (and some libraries
).