In Sweden midsummer is celebrated today with traditional food and customs. Pickled herring (sill), new potatoes (färskpotatis), sour creme (gräddfil) and chives (gräslök) is typical, served with Swedish akvavit (herb-flavored vodka, snaps). Mmmm, good! Other traditional food is salmon of course. But these days, I think anything good goes.
The real midsummer is of course on June 21, but since midsummer is a holiday in Sweden, the Swedish government decided it should be on a Friday each year, so everybody gets a 3-day weekend. Stamp of the Day are four Swedish stamps celebrating Sweden, with the midsummer one in the top left corner.
Old midsummer traditions are to dance around a pole covered in green tree leaves (birch usually) and wild-picked flowers. Then late at night, which doesn't get very dark in Sweden, young women should go out and pick 7 flowers and jump over 7 fences and then they put the flowers under their pillows and go to sleep, all without talking to anybody (if you do, it doesn't work). If you did this you will dream about who you would get married to. Believe me, it doesn't work! :) But it is fun.