Dear all game developers ever, please stop putting the following in your game. They fucking annoy me.
 
Unskippable Cutscenes 
  
This is something that always gets my goat. Unskippable cutscenes need no introduction really, we've all fallen prey to them, and they suck. You've reloaded an old save, begun the game a new or for whatever reason seemed suitable for you you just want to get to killing things. WAIT! We have a 6 minute cut scene you NEED to watch first. Why do I need to watch this? Because the game says so that's why! 
Personally this always kills the flow of the game for me, especially if it's a shooter. I usually just turn to my laptop/book for a while and keep an ear out for when the whole needless bother is over with. Now I'm in no way opposed to cut scenes mind you, they can be awesome as well as essential for plot driving but give me the option to skip them if I want to. There's really no excuse for this. I could maybe grasp it if the game recognised this was an initial play through but even then what if I've played the first few levels on my friends system earlier? huh? game!? Didn't think of that did you. 
  Unskippable cutscenes can fuck right off. 
 
Recent example that springs to mind: Shadows Of The Damned, Crysis 2
 
Checkpoints Placed Directly Before The Above 
 
This isn't just about cutscenes this one, this is more a checkpoint that's placed right before a piece of character dialogue, or a conversation with an NPC. This also only really comes into play when the game is hard. For example when playing Halo: Reach on Legendary and I will not stop dying. The only thing that's going to annoy me even more than being shot down by the same fucking Banshee 64 times in a row is hearing Jorge spout the same fucking dialogue at me 64 times in a row! 
What's worse than this though? Well if you have a game that mixes action with dialogue trees. Mass Effect or, more notably from my recent experience, Silent Hill: Homecoming. What's worse is when there's a checkpoint placed right before a dialogue tree that is followed by a boss that will kill you... alot. So each time you die you now have all that lovely dialogue to go through hitting the same responses before you can tackle the thing that did you in. If the spoken dialogue is unskippable too then we're in for a real treat! 
 
Examples that spring to mind: Halo series, Silent Hill: Homecoming 
  
More of these will spring to mind no doubt, I'm sure people have their own examples...