As I said in this support request, not having a next button when you hit a protected entry frustrates me. I went and learned some javascript and came up with the below monster link. It takes the URL of whatever entry you are looking at and goes to the next entry in that journal. I tried this on a bunch of different entries, some with weird modifiers, like thread IDs and cuts, so I think it works. Try it out and tell me if you have any problems.

Update: Since LJ changed the URLs, these were broken. Now they are fixed to work with the new URL format.

Click and drag the following link to your links toolbar:
Next Entry

I also made a Previous Entry link: Click and drag the following link to your links toolbar:
Previous Entry