I think the size that should work with most browsers is 640 wide with a variable height depending on the photo's proportions. I am hoping that this size will still be able to portray what the photographer is trying to express.
If you feel like you need to post a BIG picture to really show what you want to show then using an lj - cut is a good idea.
Keep up the great photographing! You are all doing a fabulous job.
Thanks hillarygayle Love you.