This post gives some interesting thoughts on the question of permission to put a blog in your blogroll:

… put bloggers on your blogroll that you sincerely recommend, whether or not they link back to you. Do it because you want to, not because you want something in return. Do it because you can honestly say “this is worth reading!” Remember, they are a reflection of you and your blog, so think through their inclusion.

And,

You can put anyone and anything you like on your blogroll. You can make up your own guidelines and standards for inclusion, or feature a totally diverse collection. As far as I’m concerned, there are no rules, no etiquette, and no reason to ask permission to put a blog on a blogroll. Can you think of any?

Excellent post on blogging culture!

[ blogroll ] A list of blogs, usually placed in the sidebar of a blog, that reads as a list of recommendations by the blogger of other blogs.  This definition of [ blogroll ] is from Google. 

[ bookmark ] A marker that uniquely identifies a row within a set of rows.  This definition of [ bookmark ] is from Google.