most of my friends know the majority of this story, all of them know a little.... here is the most recent addition.
My friend's X husband (keep in mind he used to smack her around in front of the children) has been trying like hell to terrorize her.  In the begining it was simple stuff like bringing the kids back later and later, then trying to break in, calling the police on her for a "welfare check" (police come by, talk to the kids, check for dead bodies etc), and calling CPS on her saying she is endangering the children.
Then he "FOUND GOD!" i had my reservations, but he seemed to be trying and she did her best to believe him.  He went as far as to return her .22 pistol, a gift during the marriage they were ending.  He promised to go with her and have the transfer of ownership done at a later date.  I think his "finding of god" lasted about 2 weeks.  During this time he was getting what he wanted.  He switched back to his evil self as soon as something didn't go his way.  Since then he has pressed charges on her(divorce court ordered stuff) to the DA.  The D.A. found no evidence and denied the charge.  
Then he pulled the big one.  In a public place he got out of hand a little with her then had the balls to claim she hit him to the police that showed up.  the police interviewd everyone around and found no evidence but he starts threatening to the officer that he'd go over his head.  The officer didn't care and would not change his mind, but advised him he could place her under "citizens arrest".  She was hauled off to jail like a common criminal and held on $3000 bail only to have the charges denied (with a nice little "do not resubmit" added after it) by the D.A.  The story spread like .223 through a battlefield.  Every officer in town got wind that night.  She was know as the woman arrested for flicking her X's pen cap off his pen.
My question is... what would be the best revenge?
I know the guy stole all sorts of stuff from his prior work.... so i could make some calls and have them look through the stuff he was dumb enough to leave with her.
He uses his HAM radio to ease drop on phone converstions (she only had old 900mhz cordless phones at the time), he has used it to open automatic doors in front of department stores and screw with poor kids at fast food drive through windows... all stuff i know the FCC would love to hear about and would probably revoke his HAM license for life.
It seems his car is the most important thing in his life... i guess his "GOD" is getting him, because it's spent the last 2 visitations with the children "in the shop".
I think she should take legal action against him for false arrest, mental anguish, and anything else she can think of.... it's really taken a toll on her.  I think the whole thing is making her stronger, but it's a slow process getting better when someone keeps stabbing you and pouring salt on the wounds.
can't tell you what i want to do... [chainsawkill]

He went as far as to return her .22 pistol, a gift during the marriage they were ending.  He promised to go with her and have the transfer of ownership done at a later date.

This bothers me, what is the consequences of the cops finding that gun? Get rid of it, he could use it(her theft, for example) against her.
As for revenge, don't get drawn into that game, there is no winners.
You never mention the kids, how he treats them, do they want to be with him,etc.
Sorry I couldn't be any more help, but I've never seen anyone win in these cases. Just time will help....fullclip

What ever happend to "Shoot, shovel and shut up?"

the .22 is no longer in her possesion... it's safe at a buddy's house.

The children... that's a good question.  Recently we have found out that they are only nice and loving on him because they think he will take his anger out on the mother if they are anything but perfect.  They are starting to realize that he's going to pull his sh!t regardless how they act.  The only one that even remembers him being around for more than 1 day every two weeks is the oldest.

Do NOT start playing the revenge game. That one has no winner.

First off,  if there is any stolen property in the house, get rid of it.  All he has to say when he gets caught stealing, is "my Ex fences the stuff for me".  This goes for any suspect "Gifts" as well, both to the wife and the children.

Document it all.  Phone calls, visitation times,  video tape him bringing the kids back, everything.

Sit down and have a talk with the local police victim affairs unit.  Inform them that the Ex hubby is engaging in a pattern of harrassment, and this is what your street officers may get called to.  It's good for the police to have intel on the idiot.

Reduce contact to the absolute minimum. NO contacts not controlled and monitored.
NO "just dropping by"
NO dinner dates,
NO meeting for coffee,
NO phone calls not Pre-arranged, recorded, and without a specific topic.
ANY topic concerning kids/money/property discussed in the company of an attorney.

He's the Ex because he's apparently a violent flake.

Treat him like you would Jeffery Dahmer.