I think Comment Email Responder is the best WP plugin out there for busy bloghoppers like me.
As for the description of the plugin, here’s one from the plugin author’s website:
The Comment Email Responder v2 is based on the work of Andrew Flusche who can up with the original concept and wrote the first iteration of this plugin. It’s purpose is to provide an easy mechanism for a blog administrator to email a response to one of the comments placed on the website. The response becomes a comment in the normal way, but also fires off an email to the commentor with the content of the response and his original comment.
Tell me that I’m starting to have memory gap, but I do need a way to remind myself which blogs I’ve left comments to. I’m a busy person and I don’t get the chance to bloghop all the time. So sometimes, even if I just surf into 5 or more blogs, I tend to forget what comments I’ve left and where I left them because it will be a long time before I get back to those blogs. By the time I get around to visiting those blogs again, I would have forgotten which post I’ve left a comment to.
Also, it would be nice to get an email back to know if the blog author already responded to the comments I’ve left.
And if you’re the blog author, it will also do good to your blog’s traffic if you’d have a better way of reminding other bloghoppers (and bloggers) that you have replied to their comments. It’s a good way of showing your readers that you read the comments they leave on your blog. It also pushes you to make comments 1:1 rather than to write a general comment, applicable to everybody.
The good thing about this plugin is that it works well with the Subscribe-to-comments plugin that most bloggers are using. I also use this plugin, though sometimes I really don’t want to be swamped with comments that I’m not interested to read, especially if I’m already tired of the topic or if the blogger has already responded to my comment. But what I do is just subscribe to the comments of a particular blog and just unsubscribe when I don’t want to read other comments anymore. I think this is the advantage of Comment Email Responder over Subscribe-to-comments: you don’t get swamped with other people’s comments. All you’ve got to receive is the response from the blog author himself.
So, if you think you need a little personal reminder that the blog where you’ve left comments to has already responded to what you’ve said, then go try out this plugin. 
