Most combinations of these are possible. Lets look at some of them.
Love without sex, commitment, or monogamy.
Can you have love without commitment? I think love in itself is a commitment unless it is unexpressed.
Sex without love, commitment, or monogamy.
To me, this is like two people using each other's bodies to masturbate. That's fine, but personally, I am unable to have sex without creating in myself the illusion of love, which is very dangerous, and has led to a lot of pain, for myself and some of my partners.
Love and sex, without commitment or monogamy.
This is what I think some people were talking about in the responses to nahima's post. Some people can do this, I can't. If I am sharing that kind of intimacy with someone, I want it to be exclusive. I should say that I did do this once, and in the end, when I found someone I wanted to be exclusive with, I lost a friend.
Love, commitment and monogamy without sex.
This is the old fashioned way. Wait until sealing the commitment with a ceremony before sex. Why wait if you are in love, committed and monogamous?
Love, commitment, and sex without monogamy.
Some couples can do this, (evidently the Clintons are one), I think I could possibly handle it if there was no deception involved, although that damn illusion rears its head again.
This probably wasn't any clearer than my previous answer.