The WAP11 and probably the BEFW11S4 could be configured as you want, (though some may disagree...) And recently Linksys has announced a really nice looking product called the WET11 which is specifically for bridging two networks together.

I recently picked up a D-Link DI-713P for $69 (normally around $129 but Fry's mispriced it--lucky me) and I've been very pleased with it. These have started to come down in price dramatically mostly related to the advent of 802.11a and 802.11g devices rolling out.

YMMV,
Tim