We normally don't mention giveaways here since the chances of winning are relatively low, but this one offers better chances - Tamron USA is having a 60 days of giveaways promotion, good until October 30. Each day, five different lucky photographers will win a 70-300mm Di VC SP lens, 18-250mm Di-II, $60 off coupon, a one-year magazine subscription, or a limited-edition t-shirt. This is one prize per winner, not five prizes per winner :)
That's 120 lenses and 60 $60 off coupons given out in two months. Plus 60 magazine subscriptions and 60 t-shirts. That means a total of 300 individual winners/prizes (60x5=300). That's a rather smart way of viral advertising on their behalf. Instead of spending advertising money on media/airtime, they are spending/giving it to 300 of their potential customers!
To enter the giveaway, you give them your name, physical address, and email address and subscribe to their eViewfinder email newsletter. Optional fields in the giveaway entry are gender and "where did you learn about Tamron products". As usual, be sure to read through all the terms and conditions before entering as different people have different preferences and sensitivities when it comes to matters of this nature.