Probably arguable whether it's 'tithing,' but it's certainly charitable giving (I'm sure they're a 501c3 org). My opinon is that 'tithing' (or the NT equivalent) is particularly for one's own congregation--keep the lights on, support the minister in his labors, give aid to the needy among your own flock, etc. Anonymous? Hm, well...depends if you want to deduct it and decrease your AGI, right? Either way, would be great to throw them a few sats every now and then...and I visit the site almost daily.