The Baldur's gate and Neverwinter Nights games always have evil options. Granted, like with most rpgs the devs devote less time and money to fleshing them out and making them enjoyable (and hence evil characters in rpgs usually tend to get less money, loot, and experience)but they were there.
Icewind Dale lets you have evil characters, but is even less in depth in catering to those that might want to play evil.
Temple of Elemental Evil: Similar situation to Icewind Dale. There are evil options-shallow, bare-bones evil options but they are there, and there is an evil ending.
Planescape Torment can be incredibly cruel at times with its evil options, and not in the typical sort of mustache twirler that seems to be the shortcut most devs seem to take. I haven't managed to complete a playthrough as an evil nameless one yet, and I generally trend towards evil characters in rpgs.
Arcanum of Steamwork and Magick Obscura also lets you be evil, although it can be even more punishing than your typical BG playthrough and has a bad ending for folks who play evil.
Geneforge 1-5: These games switch between Rebel and Shaper perspectives a bit, with 1-3 from the Shaper perspective, and 4-5 from the Rebel perspective, but one thing's for certain, both sides are completely monstrous, although it's up to the player to choose if they want to be a geneforge-mutated canister junkie with anger issues and a superiority complex carrying out assassinations and/or genocide for your equally crazy masters or someone who's trying to salvage what they think is the least bad group.
Enclave is an action hack and slash PC game with both a good campaign and an evil one, though you have to beat the good campaign to unlock the evil one.
Evil genius: Name says it all-basically you get to play as a James bond villain parody and do evil stuff in your evil lair staffed by evil henchmen. A bit tongue in cheek but very fun.
Sadly most devs seem to put the bare minimum into 'evil campaigns' possible, if they are there at all. RPGs have a chronic problem with writing everything from the perspective of a lawful good-aligned human and plopping down only token evil options. Seriously, how many rpgs have quests where the evil 'solution' is basically just 'kill quest giver and take their money'-which is usually much shorter, less complex (obviously) and less rewarding (in all senses of the word) than their good options. heck, in your average Neverwinter Nights 1/2 game you are likely to have trouble keeping your evil character out of Neutral territory if you RP them as anything other than a mass-murdering psychopath because most actions that don't involve burning all your bridges behind you (or in front of you) like a shortsighted fool result in 'good' points. You shouldn't have to murder someone to counteract the goodie points you get from being polite to the last 1-2 people you talked with.
