Prevent Contact Form Spam - No Captcha

Hey all, I need someone to do something to prevent the contact form spam I am getting for my websites. I do not want to use captcha. Please tell me exactly what your plan is in order to get rid of this spam. I would prefer that you just edit the current contact form I have - but if you need to create a totally new contact form it needs to be similar to the one I currently have (able to change colors etc). It's a very simple contact form - but the spam I am getting is unbearable. So please tell me your plan of attack for preventing this spam - at this point I just want someone who can guarantee me that the spam will be gone! Good luck...