The "Next Blog" link on the Navbar makes your blog part of the blogosphere. Someone clicking on "Next Blog" from their blog (or a third party's) randomly lands on your blog. The random nature - never the same blogs twice - makes the "Next Blog" appealing, and provides readers to new blogs.
But the random nature is a double edged sword. You never know where you're going, when you click there. Sometimes, you end up where you don't want to go. If you have a blog targeted to those of impressionable minds (children for instance), you may not want the readers of your blog next blogging from yours.
So you block the Navbar on your blog. Find the 3 lines of code shown below, that are in the template now, and add the first line of code to immediately precede them. This will be at the end of the blog header, just before the blog body. In a normal template, and without "Expand Widget Templates" selected, this will be 4/5 towards the bottom of the template. Backup the template, before, and after, you make this modification!
#navbar-iframe {height:0px;visibility:hidden;display:none} <== Add this line,
]]></b:skin> <== immediately above
</head> <== these 3 lines,
<body> <== that are already there.
Now, no next blog surfing from your blog (though still possible from others). And now, your blog becomes less of a member of the Blogosphere. You're getting readers (from other Bloggers using "Next Blog" to click to yours), but you're not providing readers to other blogs (from other Bloggers potentially using "Next Blog" to click from yours).
(Note 2007/9/4): I was officially informed today by Blogger Support
While it's not officially against our TOS, we discourage folks from removing it because we think it's a great feature with more improvements to come.Follow the above instructions at your own peril, as Blogger controls the TOS and has been known to change it. Their ball, their ball game.
Besides imperiling the future of the Blogosphere in general and your blog in particular, you lose functionality. If you make a lot of formatting changes, or new posts, to your blog, you'll notice the lack of the "Customize" and "New Post" links. And your readers may not care for the lack of the "Search Blog" link either.
But, it's your blog, and your responsibility.
If you have your own LAN, or control your computer, you can prevent use of "Next Blog", without mucking with your blog. As pointed out in Blogger Help: How can I block access to NextBlog on my network?
All you have to do is restrict access to this specific URL:
"http://www.blogger.com/next-blog?navBar=true"
All that you need is a firewall or proxy server that filters by URL. Add that specific string
http://www.blogger.com/next-blog?navBar=trueas not permitted.
You can do this for your entire LAN (by configuring the firewall or proxy server), or for your individual computer (by configuring a filtering proxy client). Result - no "Next Blog" surfing, and safer readers. And no TOS violation.
And in the long term, education of your readers would be a good idea. They need to learn that clicking on "Next Blog" may take them, sometime, where they don't want to go. Everything in the Blogosphere will be distasteful to somebody, though everything cannot be forbidden. Your readers need to know how to deal with the world in general, and the Blogosphere in particular. The Blogosphere is nothing more than a slice of the world.
Do you see the Navbar on this blog? It's here, but may not be completely obvious. If your issue with the Navbar is its appearance, try changing the colour. For a blog with a Layouts template, go to Layout - Page Elements, and click on the "Edit" link for the Navbar page element. You have your choice of Blue, Tan, Black, or Silver. Most likely, one of those selections will blend with some colour used in your blog.
