We have a similar day & website here, called "Midlands Gives" which takes place in May (though the site accepts donations on other days too). I really like how easy it makes it to donate to multiple charities at once, and to find out about local charities one may not have been familiar with. After giving to the charities I normally do, I often scroll through the "leaderboard" which lists how much each charity has received so far, looking for charities which sound good but didn't get a lot of donations so far, to help them out.