At a few IHG hotels recently I have been offered the choice of a drink/snack or some bonus points. Typically I have taken the points and they seem to make their way to my account either by being directly credited by the hotel or by them issuing a voucher like this one:

 

The only problem is that the web site in the front (ihgrewardsclub.com/deposit) doesn’t work.

Use this one instead – https://www.ihg.com/rewardsclub/us/en/account/depositpoints/