I'd suggest some of the 1200 RPM slipstreams, they're amazing case fans, move a ton of air, they just shouldn't be used on heatsinks or rads.
EDIT:
1200 RPM, nice and quiet http://www.newegg.com/Product/Produc...82E16835185058
1900 RPM, overwhelmingly noisy at times http://www.newegg.com/Product/Produc...82E16835185060
1600 RPM, a good balance IMO, I run my 1900RPM's at 1550RPM and they're nice and quiet http://www.newegg.com/Product/Produc...82E16835185059
EDIT:
1200 RPM, nice and quiet http://www.newegg.com/Product/Produc...82E16835185058
1900 RPM, overwhelmingly noisy at times http://www.newegg.com/Product/Produc...82E16835185060
1600 RPM, a good balance IMO, I run my 1900RPM's at 1550RPM and they're nice and quiet http://www.newegg.com/Product/Produc...82E16835185059