As a consumer, what you have to do is create an account with the website, pay via credit card or bank deposit, print and keep the voucher sent to you by email, and schedule your visit for when you decide to use your voucher. Note that merchants place different expiration dates on their deals. Some have a life of as long a year. Others must be used within three months. So it's best to devise a system to keep track.
Anyway, I bought the following deals since learning about this phenomenon:
Also bought a couple of vouchers for a slice of Polly's cake and a large drink at just PhP110. Sobrang sulit. Here we are enjoying cake at Polly's courtesy of my Groupon vouchers. Please excuse my sister's expression. She's the weird one in the family. Heehee
If I missed some websites in the list above, do not panic. frugalpanda.ph came up with the brilliant idea of collating all of these deals in a single website. Now I don't have to visit the discount websites one by one. I just go to frugal panda and look at recent deals from all of the discount websites there. Coolness.