In a sign that pressure is mounting for retailers to offer free shipping, online shoe seller Zappos is offering free overnight shipping for your lifetime when you register to become a VIP today only.

Standard shipping is free both ways on Zappos. Sign up to become a Zappos VIP here.

Joining is free and requires you to share an e-mail address, name, and create a password. The offer expires at midnight PST Dec. 1.

Here's a pair of Seychelles gray shorty boots that I'd like to own. Zappos has them for $114 and with my new VIP status I could try them on tomorrow.

Bargain secret: Zappos sells its overstock at 6pm.com.

Caveats: not available for shipments to Hawaii, Alaska, U.S. Territories, P.O. Boxes or AFO/FPO addresses. Orders placed before 1 p.m. Pacific time (4 p.m. Eastern time) on a business day will be delivered the next business day but orders placed after 1 p.m. PST will be delivered in two days. For example, orders placed prior to 1 p.m. Pacific time on Monday will be delivered on Tuesday, while orders placed after 1 p.m. Pacific time on Monday will be delivered on Wednesday. Orders placed on Friday after 1 p.m. Pacific time, Saturday or Sunday will be delivered on Tuesday. Business days do not include holidays.