I'm not a Libertarian, although there are things attractive to me about the Libertarian ideas. The big problem for me comes down to defining victim in this statement. A lot of Libertarians I run across seem to feel that the victim needs to be a precisely identifiable person or set of people and that the harm done needs to be a concrete use of force.
I, however, feel that there are some cases where merely putting someone at risk of harm should be a crime. I also feel that there are legitimate instances of crimes against society as a whole. Unfortunately this kind of stuff usually gets down into discussions about morals and the Libertarians balk at "having my morals forced on them".
The actual Libertarian platform to me is a little more reasonable in my views:
Principle: Government exists to protect the rights of every individual including life, liberty and property. Criminal laws should be limited to violation of the rights of others through force or fraud, or deliberate actions that place others involuntarily at significant risk of harm. Individuals retain the right to voluntarily assume risk of harm to themselves in the exercise of free choice.
I like the inclusion of not only force, but also fraud, and the "risk of harm" part makes this a lot more palatable to me than what I seem to hear from individual Libertarians. Of course, qualifying it as "significant risk of harm" opens it up to all kinds of vagueness of interpretation.
For example, how to Libertarians feel about espionage? Suppose an individual sells stolen plans for a weapons system to another nation? Is he simply guilting of misappropriating intellectial property, a property rights violation? Or has he put the entire country at "significant risk of harm"? What if the other nation never uses the plans and so no one is actually at risk? What if he actually sells them to a double-agent so they never really fall into enemy hands? Was anyone really at risk then? Doesn't his intention count for something?