Typically they were placed in the middle of town with their arms and head through a wooden block. If they did something horrific there were a number of torture devices: The iron maiden, tied to a tree and a horse tied to your limbs, red hot branding, suspension by your arms, items being shoved under your fingernails, guillotine, gauntlets and so on...
also they had something called the spider that is just an advanced breast ripper. the woman's breast would be attached and then they would pull her away and it would rip it off.
the pear of anguish was a device that go into someones mouth, or a vagina/Angus then when you crank the lever it would open and rip the skin open from stretching it. a person would normally die from infections.
During the Early Middle Ages, people were subject to a combination of Germanic Laws and Roman Law. In some respects, Germanic laws were often less severe. For example, there was the concept of weregeld, which prescribed the fine a person had to pay for killing someone. If you killed a freeman, you were fined 200 solidi. If you killed a priest, you were fined 300 solidi or 400 if he was saying mass when you killed him. A member of the nobility was 1200 solidi and up. Killing the king would set you back 30,000 solidi, 15,000 to his family, and 15,000 to the state. Evaluating killing a person in terms of a fine may seem brutal, but that is not the point; kings were presiding over legal systems that would fine a person who murdered them. This came to an end, of course, but it was the way things were for the first few centuries of the middle ages. (see link)
We have the idea of burning a witch at the stake, and this no doubt happened. After all, it happened to Joan of Arc. Nevertheless, in the Early Middle Ages, the legal codes of the Franks and the edicts of the Church forbade belief in witchcraft, and so execution for witchcraft was illegal since legally witchcraft did not exist. (see link)
Our views of legal proceedings of the times are also a bit askew. There was a concept of Compurgation which operated into the High Middle Ages. If a person charged with a crime swore an oath that he was innocent and was able to produce at least 12 people who would testify that they believed the oath, then he was likely to be regarded as having defended himself successfully. (see link)
There was also the concept that clergy were exempt from secular courts and had to be tried by the Church. There were ecclesiastical courts set up for this purpose, and they were operated in a very different way than secular courts, because they were more merciful and aimed at correction rather than instilling fear. There was a problem of proof that a person qualified. Originally this meant that a person had to show up for court dressed like clergy, but anyone could do that, so it was decided that the benefit would be given to anyone who was literate, and a test was instituted. Benefit of Clergy, implying immunity from secular prosecution, was eventually extended in England to anyone who could read the 51st Psalm. As far as I know, there was no test to find out whether the person had memorized the 51st Psalm. The law establishing this came just about the same time a Pope banned clergy from participation in torture. So anyone who was literate could, in theory, avoid torture. (See link)
In addition to this, there was sanctuary. If a person was being pursued, he or she could hide out in a church or monastery. In many times and places, the person charged with a crime had a limited time in sanctuary, but in other times and places a person could simply stay in a monastery, and this is especially true for a person who was not a fugitive from the law but from abuse or danger. Medieval queens sometimes did this to get away from their husbands, and it was effective.
I have read that punishments of the Middle Ages included such things as wearing a mask with a pig's face on it for a prescribed period of time, but I have been unable to confirm this.
I am not going to portray this as anything like a description of what medieval punishments were. But clearly they were more varied than one might imagine.