Unsubscribe.com has just launched their BlackBerry app that simply allows you to remove yourself from spam/mailing lists with a few simple clicks. Unsubscribe.com has been specializing in this for a while now with Outlook, Gmail, Thunderbird and more.
You can simply go to Unsubscribe.com and download the application to your BlackBerry, and from there when either in your Messages folder or directly in one of your email, the Unsubscribe option will be in your menu.
Once you click Unsubscribe it automatically unsubscribes you. There is a free version which lets you block 5 emails a month. Subscriptions are available $2.95/month, $19.95/year or $149.95/lifetime, and these allow you to block unlimited emails.
You can find more information, OTA download link and subscription information on the Unsubscribe.com website. They have also done a great job adding compatibility with a version for OS4.2 and below, as well as OS4.5 and above.