Normally a "follow" link is a vote for the site you're linking to. A "nofollow"
link basically is supposed to mean that you're not giving the linked site a vote.
The search engines will follow the nofollow links to find new info, it's just
that they won't add a vote to that site, so that site gets no boost in
If you go here: http://www.quirk.biz/searchstatus/
you can grab
a widget for your Firefox browser that will let you see at a glance which
links are nofollow.
As far as links go... I have CommentLuv installed which will look at your
blog and try to grab the title, and link, of your last blog post and then
it'll append it to your comment.
KeywordLuv is similar, but puts a keyword lnk in the name field of your comment.
I have the DoFollow plugin installed, so comment links do get a bit of link juice.
But consider that if you leave good comments wherever you're commenting
then you'll get clicks on your link, so the follow part isn't so important.
Search ranking are lovely, but you can get a long of traffic from other
sources and nofollow doesn't mean a thing with those.