Here are some implementations of the SDI being used (active at the time of writing)
The Pluto Appeal
The Pluto Appeal is aiming to raise funds to meet the cost of a piece of hospital equipment. Using the SDI, the donor is asked to enter the amont they want to give and then directed from the Pluto Appeal website over to JustGiving to make their donation. The donation, once complete, is queried via the API, and the Pluto Appeal graphic is updated by another pixel.
IHG Shelter In A Storm
The Intercontinental Hotel Group Shelter in a Storm Programme provides hotels with guidance on when and how best to respond when disasters occur. The IHG Shelter Fund is a pool of resources built up by direct donations made throughout the year using the SDI to drive donations in multiple currencies.
BST Summer Time Gigs
The aim was to enable fans to donate to the chosen charity of performing artists and receive a gig ticket in return. So using the Simple Donation Integration service, fans selected their artist of choice and were redirected to JustGiving to donate and subsequently taken to a hidden ticket platform to order their unique ticket.