Unless you want to cross-compile practically the entire known Gtk+ GNOME universe, grab the following binaries from http://ftp.gnome.org/pub/gnome/binaries/win32 (some of them are under the dependencies directory):
enchant-1.4.2-tml.zip
enchant-dev-1.4.2-tml.zip
fontconfig-2.4.2-tml-20071015.zip
fontconfig-dev-2.4.2-tml-20071015.zip
freetype-2.3.6.zip
freetype-dev-2.3.6.zip
GConf_2.22.0-2_win32.zip
GConf-dev_2.22.0-2_win32.zip
gettext-runtime-0.17-1.zip
gettext-runtime-dev-0.17-1.zip
gnome-vfs_2.24.0-1_win32.zip
gnome-vfs-dev_2.24.0-1_win32.zip
gtk+-bundle_2.14.7-20090110_win32.zip
gtkhtml-3.18.2.zip
gtkhtml-dev-3.18.2.zip
gtksourceview-2.4.1.zip
gtksourceview-dev-2.4.1.zip
libart_lgpl-2.3.20.zip
libart_lgpl-dev-2.3.20.zip
libbonobo_2.24.0-1_win32.zip
libbonobo-dev_2.24.0-1_win32.zip
libbonoboui_2.24.0-1_win32.zip
libbonoboui-dev_2.24.0-1_win32.zip
expat_2.0.1-1_win32.zip
libglade_2.6.3-1_win32.zip
libglade-dev_2.6.3-1_win32.zip
libgnome_2.24.1-1_win32.zip
libgnomecanvas-2.20.1.zip
libgnomecanvas-dev-2.20.1.zip
libgnome-dev_2.24.1-1_win32.zip
libgnomeui-2.22.1.zip
libgnomeui-dev-2.22.1.zip
libgnurx-2.5.zip
libiconv-1.9.1.bin.woe32.zip
libIDL_0.8.11-1_win32.zip
libxml2-2.6.27.zip
libxml2-dev-2.6.27.zip
ORBit2_2.14.16-1_win32.zip
ORBit2-dev_2.14.16-1_win32.zip
popt-1.10.2-tml-20050828.zip
popt-dev-1.10.2-tml-20050828.zip
WebKit is required also, and our friends at OpenSUSE have built it for us:
http://download.opensuse.org/repositories/windows:/mingw:/win32/openSUSE_Factory/noarch/
From there, grab:
mingw32-libwebkit-1.1.7.noarch.rpm
mingw32-libwebkit-devel-1.1.7.noarch.rpm
mingw32-gnutls-2.6.6.noarch.rpm
mingw32-libgnutls-2.6.6.noarch.rpm
mingw32-libgnutls-devel-2.6.6.noarch.rpm
mingw32-libsoup-2.26.2.noarch.rpm
mingw32-libsoup-devel-2.26.2.noarch.rpm