Currently my RPG group is playing the Temple of Elemental Evil (original). My paladin is a worshipper of Pelor, and he's a rough-and-ready type. He doesn't wear polished armor since he likes to try to sneak up on the enemy, if able, and he carries a battle-axe instead of the typical sword. Although he doesn't practice it, he tolerates shady dealings such as his companions enjoyment of ladies-of-the-night, since it isn't against the law to do so. Now to the big moral question...
We used to make an effort to take those that surrendered to us and bring them to Hommlet for imprisonment and trial, but they would either be released due to corrupt guards, or people on the outside would slay the guards and free them. The good people were frightened of the more corrupt ones in their midst, making a trial impossible.
After a few incidents, my paladin came up with a solution. He has a speech ready when he enters a room full of low-lifes or when humanoids surrender after a few rounds of combat. It goes like this: "Gentlemen, you have three choices. First, you may surrender yourselves to me and I will place you under arrest in our fortress (converted Moat House). There you will receive food and a cell to rest in, but will have no trial until we have cleansed this land of evil. This may be a long time, but afterwards you will be tried by the good people of Hommlet. Your second option is to agree to repent your evil ways and convert to Pelor. You will still be kept in a cell, but we will see to your religious education and free you when we are confident that you have seen Pelor's light (by using Detect Evil). Finally, I can judge you here and now. I warn you that my judgement is harsh, and it will most likely end with your execution. You will have your say, and if I deem you guilty, I will allow you an hour to pray to your god before giving you the axe."
So far I have had a lot of surrenders, one conversion, and one execution. The execution shocked the party. I put a river pirate on trial and his only verbal defense (after he asked for the trial) was to spit at me. So I had him locked in a room to pray for an hour, drug him out to the edge of his vessel, tied him down, and told him to say his last prayers to his sea god and asked if he had any last requests. He asked to be thrown into the sea he loved, and we had a short dialogue of mutual respect, before I gave him a moment to make his prayer, chopped his head off, and kicked both pieces of his body into the river.
The rest of the players stared wide-eyed and thought it a very un-paladin thing to do. Given the state of law in the area and the danger of keeping the really evil characters in the cells, the paladin thought it was for the best. Right now the 'Three Choices' is a running gag.