The US has been issuing stamps with the theme love for many years.
Forever love (2015). Video story of the designer's view on forever love (4 minutes). I have these stamps, just haven't used them yet. I prefer the white version - with the small 'forever' and '2014' in silver (scans as grey). I still think it's a bit odd that the heart says forever and there is also forever written below.
Here are some I sent and received.
Cut paper heart (2014). The one from Olathe has a unique digital color St Valentine's day postmark. The story behind the design is here.
Sealed with love (2013)
The 2012 stamp is Love ribbons. Out of print, a sheet of 20 stamps now sells for over three times the current first class price.
This 20c Love stamp is from 1984. Sadly many of the vintage stamps don't always stand up to the modern sorting machines, so this example is a little torn.
Of all the love stamps, I think this one is my favorite set, Garden of Love from 2011, even though I have never received any. A very clever design, with a lot of variety in the set.
Just noticed that USPS Stamps has a feature on Valentine's day mail artists.
I'm not sure how long La Poste has been doing this, but they have a series of Valentine heart-shaped stamps designed by famous design houses (like Chanel, Hermes etc).
Many of the designs can be seen here. It's an interesting concept to have commercial enterprises design stamps (and have their names on them - great advertising) - I can't see this happening in the US.
The 2015 set is designed by Jean-Charles de Castelbajac.
Rubber stamped hearts from Katerina N, all the way from Greece. A big chunk of background on the Greek 'European Youth Capital Thessaloniki 2014' stamp is pink, does that count?
Enjoy the rest of Valentine's Day, everyone.
Last minute update: Eva blogged about Dr Turing's Love Letter Generator. If you've been at a loss for the perfect way to express your feelings, then this is for you - it's not too late!
The one I had Dr Turing's machine send to myself: