I'll provide a few more, but this is not the sum total. There are a lot of changes, and most of them are completely unnecessary.
One that comes to mind right away was in The Two Towers where Aragorn is wounded during a battle with warg riders on the way to Helm's Deep. Aragorn is separated from the company and floats unconscious down some stream, only to wake up, climb back on his nearby horse, and ride off to catch up with everyone else. There is simply no need for this scene. It is a completely unnecessary invention of the filmmakers and adds nothing to the story.
Later in TTT the elven archers show up at Helm's Deep for the coming battle. Then there's this sappy/crappy scene where poor Haldir is cut down. Ugh. And the ridiculous shield-sliding stunt Legolas performs in that battle… dumb.
Another change that makes no sense is the way Jackson handles Narsil/Anduril. There's no reason for Aragorn not to take TSTWB at the outset of the quest.
There are about a dozen different changes to the character and nature of Faramir throughout the films that are wholly unnecessary. We've already seen Boromir's struggle against the Ring. We know that Faramir is more wise and more self-controlled than Boromir, but in the movie Faramir tries to take the Ring as well, and he does it in Osgiliath (unnecessary change again) rather than having all of his interaction with the hobbits at his Ithilien hideout.
While at Osgiliath, Frodo has some one-v-one battle of wills against a Ringwraith. Wholly unnecessary invention of the filmmakers.
Having Shelob appear only in the RotK is so wrong it's almost criminal. The cliffhanger ending to TTT was brilliant. With a year between the movies it would have whetted the appetite for those not already familiar with the story even more. I have yet to see a reliable explanation for why Shelob was moved from one movie to the other.
I could go on and on. I happened to catch TTT over the weekend when it was on again so those all jumped out at me. There were quite a few changes made to the Siege of Minas Tirith as I recall, and another absurd Super Legolas moment when he shot that Oliphant full of arrows, and another stupid change where Arwen rescues Frodo at the fords of the Bruinen in FotR instead of Glorfindel. I get that it could be troublesome to have too many characters that come and go, but Arwen? Come on.
I don't have a problem so much with condensing characters and eliminating scenes like The Scouring of the Shire and the Bombadil/barrow scenes. Bombadil in particular would simply confuse anyone who hasn't read the books… heck, even people who have read the books don't know the point of that whole scene.
Overall I thought Jackson's "take" on LOTR was brilliant. For everything he got wrong he probably got three or more things right. Some of the changes he made I liked quite a bit, and some I thought were horrible misrepresentations of the general story and/or specific characters.
Keep wreves in General Talk in 2011!