Facebook has extended its shopping spree by buying Tagtile, a loyalty and direct marketing solutions designer for businesses. Tagtile is the second company Facebook has bought this week. It bought social photo-sharing mobile app company Instagram on Monday.

Tagtile is service for businesses and customers. Businesses can set up the service using a Tagtile “kit” which comes with a funny-looking cube that only needs to be plugged into a power outlet. Customers can then “tap” their phones on the cube at check-out counters, registering their visit with a business. The business can then use the information however they want, presumably to give discounts, coupons, or other incentives to come back and “tap” again.

A statement yesterday on Tagtile’s website stated:

Today, we are happy to announce that we are joining Facebook, and that they are acquiring substantially all of our assets. It’s a huge opportunity for us to take our goal – helping businesses grow – and do it on a much, much bigger scale than we could have on our own.

We won’t be taking on any new customers as of today, but the service will continue to work as is for now. We’ll be reaching out to customers directly once future plans are set, but Tagtile as it exists today won’t be a part of what we do at Facebook.

I can see how Tagtile could be very useful for businesses seeking to keep track of their customers, and also useful for customers whose wallets are overflowing with grocery store, gas station, and various other “rewards” cards. Not to mention all those buy-10-get-one-free coffee, sub, and cookie hold-punch cards. The real question, with all of the privacy paranoia going around, is whether a Facebook branding would help or hurt the service.

Purchasing these companies is an interesting move for Facebook, and reminds me of they way Google gobbles up smaller start-ups that are already implementing services it might want to see on its sites. There’s no arguing, though, that Instagram would fit very well into the Facebook mobile app for smartphones. Also, Tagtile would seem to go hand-in-hand with the “Offers” service Facebook began rolling out this week.

There is no word yet on what Facebook has paid for Tagtile, but I’m willing to guess it is much less than the shocking $1 billion it paid for Instagram.