[woodsyi]

If you are getting dipole speakers like Maggies, I would seriously look at Duke's Swarm.  Here is a used set on sale for $500.  I use them with a pair of big Soundlab electrostats and they blend in very well.

I would also suggest that you get LCRS speakers before you get the sub(s).  You can enjoy good speakers without subwoofer but you really can't enjoy subwoofer without decent speakers.   

[acresm22]

I've always thought these NHT Verve subs are interesting...have no idea how they sound, but the price is right.

http://cgi.ebay.com/NHT-Verve-Sub-Dual-Aluminum-10-Woofers-200-Watts_W0QQitemZ380187989239QQcmdZViewItemQQptZSpeakers_Subwoofers?hash=item5884f854f7

[eg1]

For most folks I'd recommend a sealed sub, like an ACI Force or Titan. However, to match your speakers I might suggest this instead, supposedly a very fast sub:

TBI Magellan VIP powered:

http://www.audiogon.com/cgi-bin/cls.pl?homesubw&1269136722&/Tbi-Magellan-VIP-powered-sub;-

Thanks everybody for all the suggestions -- I think I am going to try this one first.

[eg1]

We hooked this (http://www.tbisound.com/dsp_products_subwmagvipsu.asp) unit up (purchased from bushbison) and are running a 3.1 system with older, fairly bass-heavy speakers. At first we set the gain too low on the sub, and when we ran Audyssey the system had to really increase the output (+9) to that channel. The sub was clearly working, but was too low to be effective, so we increased the gain (not quite all the way to the top) and ran the Audyssey again. Now that channel is only at +1 and the system sounds much more balanced. I could really feel the effect on Diana Krall's "The Look of Love" and other jazz recordings featuring standing bass. Very musical, never muddy, and always in sync with the rest of the speakers -- no lag or other annoying artefacts. I am hoping that when I switch to a set of planar ribbon speakers in the near future that this sub will be able to provide the bass that they lack and that it is quick enough in response to pair well with them.

Thanks to all for your assistance!