Packed Party offers curated & themed packages that you can purchase and send to friends. It does seem to cater more toward women, but the concept is solid.
They have packages for birthdays, "pity parties," just-because-I-miss-you, thanks, bridesmaid, congratulations, pampering and break ups.
Long distance friendships? Nailed it. Of course you could assemble your own gift, but sometimes people need a pick-me-up right away. They offer 2-day or UPS Ground, and packages are around $45 each.