If you have a strong advocate among your references, you may want to consider this resume-enhancing technique. Have your reference fill out a series of Post-it Notes (3" x 3" size works best) with the following handwritten note:
Excellent Candidate—Definitely Interview
They then sign their name (and title, if appropriate). This technique works because of the internal referral network at most companies which is supported by the Post-it Note-and-pass-along method of delegation. I receive memos and other notes from my boss with similar directions attached via Post-it Note.
This technique works best when the resume is being sent to a contact who knows your reference. But it can be used virtually anytime you want an extra impact with the "instant recommendation."
An alternative would be to have your reference write: "Highly Recommended—Definitely Interview" on their business card which then is attached to your resume. Either way, it sends the very unconventional message that more people think highly of you than just you. Remember that the words of others said about you will almost always carry more weight than your words alone.