i am in the same boat with my almost 3 year old...let me tell you what I did...
He had bouts of allergies and ear infections since he was small so part of his issue was discovered at the ENT when his hearing test came back pretty bad. That was right around when he turned 2. He had tubes put in and it fixed the hearing problem (not saying this is your issue, but just hear me out :) ) Now to move onto his delay...the delay was due partly to his hearing issues. Plus he's a boy and boys seem to talk slower than girls do anyways (my experience with my first son too! he's 5 now). We contacted Early Intervention and had him start speach therapy. This helped greatly and it's free. I believe every state has something like this. He had therapy for about 6 months and you can definitely tell a difference. Also, he's in day care with a bunch of other kids that talk so that helps too. Things that YOU can start doing to help right away are things like telling him everything that you're doing. Like if you know he wants juice, tell him "You want some juice? OK I'm opening the refridgerator, getting out the juice, pouring it in the cup and here is your juice in your cup!" Also, start teaching him sign language. This helped us a lot. We started teaching him basic words for things we knew he wanted, like hungry, cup, banana, apple, mom, dad, etc. There's a ton of free resources online plus Early Intervention can help too.
I understand how you feel...it's extremely frustrating for you but you need to imagine how he feels too...he knows what he wants but can't tell you what it is. If you were in that situation, you would scream and cry too! just don't get angry or frustrated...this is a difficult time for both of you. He'll get it soon and you won't be able to shut him up!