Let your continual mercy, O Lord, kindle in your Church the never-failing gift of love, that, following the example of your servant William Wilberforce, we may have grace to defend the poor, and maintain the cause of those who have no helper; for the sake of him who gave his life for us, your Son our Savior Jesus Christ, who lives and reigns with you and the Holy Spirit, one God, now and for ever. Amen.
The Gospel, which also sums him up nicely:
Jesus said, "When the Son of Man comes in his glory, and all the angels with him, then he will sit on the throne of his glory. All the nations will be gathered before him, and he will separate people one from another as a shepherd separates the sheep from the goats, and he will put the sheep at his right hand and the goats at the left. Then the king will say to those at his right hand, `Come, you that are blessed by my Father, inherit the kingdom prepared for you from the foundation of the world; for I was hungry and you gave me food, I was thirsty and you gave me something to drink, I was a stranger and you welcomed me, I was naked and you gave me clothing, I was sick and you took care of me, I was in prison and you visited me.' Then the righteous will answer him, `Lord, when was it that we saw you hungry and gave you food, or thirsty and gave you something to drink? And when was it that we saw you a stranger and welcomed you, or naked and gave you clothing? And when was it that we saw you sick or in prison and visited you?' And the king will answer them, `Truly I tell you, just as you did it to one of the least of these who are members of my family, you did it to me.' "
Consider celebrating the day by giving to an abolitionist fund, devoted to ending modern-day slavery (of which there is a great deal), like The Amazing Change Fund or International Justice Mission. You can also earn money for IJM by using GoodSearch for your search engine for a while and making it your charity. This is a way to raise funds for them (about a penny a search) without even having to dig into your wallet.
Another way to remember the great social reformer is to re-read his famous 1789 Abolition Speech