Thanks to all for sharing their information. I think link juice is the value which float from link you got.
A link building is called the link juice.You can get link juice from a variety of sources. Some of it can be generated yourself by submitting to social media sites like Digg, Reddit, and Buzz.
You should have to go with link building techniques for your blog. This technique will help you to make link juice for your blog. You can do this with the help of directory submission of your blog, bookmarking of your blog, web 2.0 submissions, bookmarking of web 2.0 links of your blogs...
If we can get multiple back links from same c class ip then we can called it as a link juice. eg. Suppose we get back links from one blog and also get back link from another blog then its only one back link but link juice increases.
Well, link juice is all about getting quality links to your site, if you managed to get links on high pr sites then of course you are getting better link juice, which has better weight in SEO and ranking in Google.