A few days ago I installed the "NoSpam!" add-in for vBulletin. If the past couple days are any indication, this should reduce the spam in here, it seemed like I was deleting several per week.
I have seen no spam in the forums and no spam in the Contact Us form.
In addition to the Image Verification for registrations (somehow bots get through this? technically it's difficult but vBulletin is a huge target so it's a tasty hack), NoSpam! just adds an arbitrary question during registration and on the Contact Us form. I put in some simple math e.g. What is 1+2 ? Acceptable answers could be 3 or three.