Canada - Rothesay, NB

I really love it when I get a letter with a miniature or souvenir sheet is used on the cover.

Issued on May 17, 2012 the souvenir sheet above was issued to celebrate 100 Years of the Calgary Stampede. It bears the permanent domestic rate stamp (CAD0.61) showing a horse with classic western riding gear and the US rate stamp (CAD1.05) showing the 2012 Calgary Stampede belt buckle.

The other stamps used to make up the postage was a block of CAD0.05 northern bumblebees from the Beneficial Insects series (issue date October 12, 2007). The first in this series, this set of low value definitives also feature the convergent ladybug, the Canada darner, the golden-eyed lacewing and the cecropia moth. 

India - Hasthampatti

A special stamp sent as an exchange on a special day - 12.12.12. 

On the cover is another miniature sheet, this time issued on October 12, 2012 to celebrate Philatelic Day. As for the other stamps, I can't seem to find any information on it so if you know when this was issued could you kindly point it out to me.

Czech Republic - Olomouc

This cover from the Czech Republic has an extra number making the date stamp 12.12.12.12. I don't actually know what the extra 12 is for - perhaps this was mailed at 12 o'clock on December 12, 2012?

The stamps used on the cover were issued on November 7, 2012 featuring images from Ctyrlistek in the King's Service. Ctyrlistek is one of the most popular children's comic books first published in 1969.

To make up the postage, the sender also used a 1Kc stamp from the May 9, 2007 flowers issue. 

Estonia - Tallinn, Toompea

For lovers of trains and train stamps, a beautiful cover with a special 12.12.12 date postmark. The envelope also shows the Sindi rail - a 1928 road bridge over the Parnu River.

The stamps are from a joint issue of Estonia, Lithuania and Latvia celebrating railway bridges - issued October 25, 2012. There are four stamps in the set howing the Narva Bridge in Estonia (EUR0.45 and EUR1.00), the Carnikava Bridge in Latvia (EUR1.00) and the Lyduvinai Bridge in Lithuania (EUR1.00).