I see lots of antennae that are rated for 2.4Ghz 802.11b/g but no mention of support for n.
I saw this on ebay (will it work?):
<a href="http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=250523672562&ssPageName=STRK:MEWAX:IT">9db external antenna"</a>
I like the magnetic base, and am looking for that (mount the antenna up high away from the router).
Have an Asus RT N16 so it is 2.4Ghz only; I use mixed g/n.