Yaaaay! Someone refered to my website! hehe
You can get a recommendation from anyone. The board looks for content and value in what is written about you. It is better to have a well-written and enthusiastic LoR from an O-3 than it is to have a mediocre and half-hearted LoR from an O-6. The higher ranking thepeson is, the more weight it can merit, especially if you have an Admiral hooking you up. But, in general, they want content and good exmaples as to why you should be considered for OCS. You can even get one from your college professors, prior employers/bosses, ect. Here is an example of an LoR:
To: The Officer Selection Board
I have been a close friend of John Smith for well over fifteen years now. He is an exceptionally intelligent, well spoken, insightful, logical, talented, and motivated individual.
Back in high school, our classmates voted John as the most likely person to succeed. Without a doubt, nothing has changed in that regard. John is currently the most educated person out of our 300+ classmates with a degree in Law. His various talents and intelligence have always exceeded those of his peers, no matter how difficult the endeavor was that he has set out to accomplish.
John is a born leader and he has proved this quality in numerous groups and settings ranging from athletics, to academics, to community projects. He has a strong morals and his integrity is of the highest caliber. Regardless of what he is doing, I would feel confidant and secure in knowing that John was on the job to give his 110%.
John is one of the most athletically gifted people I have ever known. He has been running in competitive track since grade school. He still races and competes at a world-class level to this very day. He is a gifted writer and has written several novels in length surpassing 500 pages. His ability to communicate eloquently is an essential attribute to being a good military officer. He works well with others and his amiable personality allows him to communicate well with those around him. His dedication to excel in such activities speaks volumes of his motivation and desire to be the best at everything he does.
I strongly believe that John Smith is an outstanding candidate for a commission and appointment as an officer in the United States Military Branch. He has the physical and moral courage, the intellect, the flexibility, and the motivation to perform superbly in any position of substantially increased responsibility. There are few people in the world that I have come across that I would advocate this passionately. I truly believe that John and his talents would be a major asset any organization he chooses to belong to. I strongly recommend him for Officer Training selection and a commission in the United States Military Branch. If you'd like to discuss his attributes in more detail, please don't hesitate to contact me via e-mail, by phone, or by written letter.
Very Respectfully, (writer)
Something like that. They want to hear about your accomplishments, goals, athletic and academic achievements, community service, moral fortitude, and all that good stuff. They want a recommendation from someone who knows you, someone that can provide a little bit of insight and express that you are a notch above everyone else.
"The object of war is not to die for your country but to make the other bastard die for his." - General George Patton (1885-1945)