Usually, I get on the highway, already accelerated (sometimes even going faster than some of the cars already on), and move in quite easily.
There's been a few times where I've nearly had to stop at the end of the
acceleration lane because an asshole either decided not to let me in, was talking on a cell phone (most people don't seem to pay attention with that, there are some exceptions

) or jacking off, or whatever the hell they're doing. It's not cutting off, it's common courtesy. If someone has just gotten on the highway, slow down and let them over. If you don't want to slow down, move over one lane. It's that simple.
I also have a problem with people who don't use blinkers. If I see someone with their blinker on, I will usually slow down, if possible, and let them over. Usually, I could be going fast, and some jackass who doesn't use their blinkers decides to move over quite quickly, completely surprising me, sometimes nearly killing me. Use your fucking blinkers before you end up dead.
Yeah, that's my rant on stupid drivers. I'm trying to control myself and be courteous when I drive, but it's hard most of the time, with the amount of idiots on the road.