Any good ways to collect emails offline?

For the purpose of list building, was wondering if anyone had any experience with this.

It depends on the nature of your offline business. I've built some email lists for some offline retailers in the past. you offer an incentive at the point of sale that the customer has to go online to sign-up to get. Usually a discount coupon or something similar (even physical product that you got at closeout). When they opt-in (double opt-in) you can then begin to email them your offers.

It will depend on the type of offline business you have...but it can be done and the list is usually quite responsive.