Hugs.tf -- an annual TF2 charity event supporting Special Effect -- is returning on April 21st and runs through April 22nd. Although it's not live yet, you can get in on the action early, as donations are now open!
As usual, you can donate with either cash or TF2 items. There is a spiffy medal up for grabs for anyone who donates a combined total of £10 or above. This threshhold can be reached by donating through any method (for example, donating £5 in cash and £5 in items will earn you a medal).