I just got an e-mail from MercadoLivre in Brazil saying Happy Birthday! Obviously it was sent earlier, as my birthday was yesterday, but that's nice of them. At least, I *think* that's what it said!! Hoje é um dia especial e desejamos a você um... Feliz Aniversário!
Mercadolibre Mexico does that too. It's quite cool, he he. Thought it is also a suggestion for you to sell your presents on the site. (It says that, literally) Happy Birthday
Mercado Livre is nice but their paypal(mercado pago) sucks so much that I will never use that again. Another think that sux are their taxes and subscribe form. Thanks to that, there are lots of "phantom" buyers/sellers.