Here's one thing that's worked for me before for business-related spam, so if you feel like spending the time...
First off, find out who the email is from. Don't trust the email address as this is very easy to fake. In the body of the email, it should reference who it really is, because they want your business. If it's a web site, make a note of it. If it's a physical address, try Google really quick to find that company's website. There are several trace route programs available on the internet. I usually use the one at easynews.com. Enter the IP address of the spammer and start the trace. This will list every computer that packet of information goes through to get to thier website. The bottom entry is the spammers site, but more importantly, the line right above that is the spammers' ISP. Then send an email to that ISP saying "I have been recieving unsolicted email from <<insert name here>> We have not requested anything of this sort from this company." Modify how you feel best, but remember this is going to the ISP, not the spammer, so be polite, and you just might get some good results. Most reputable ISPs will have an anti-spam policy and will try to help. I've gotten some spammers out of my email box with this proceedure.
By the way, If the spammer is overseas, don't waste your time composing the email as they will more than likely not even deal with it.
One last thing - Never click on the "click here to remove" line on the spam emails as this will not remove you, but verify you email address and you'll just get spammed more