|Comment aggregation is the little-known second cousin in the world of RSS feeds. The basic idea is simple: Provide a way to keep track of comments that have been left on other people's blogs. For example, if I leave a comment on somebody's website, I might want to know if anyone commented after me or in response to me. Sure, I could add each of those posts' feeds to my feed reader, but that sounds ugly and complicated. There are a few websites that claim to do this for me:
coComment seems to be the best because it was the first (that I know of) and it offers a ton of features. It comes with a nice interface and a fancy bookmarklet. But there's one caveat: You only see responses to your comments if other users are registered with coComment. In my opinion, the best way to ensure your product's failure is to require everyone to use it.
My rating: 1/5 stars
Co.mments is pretty simple: It has a text box where you paste the link you want to track. It figures things out and displays how many comments the post has and how many of those are new. It has a bookmarklet for your browser and has a feed for your conversations. No tweaking necessary. No mass-cooperation to use.
My rating: 5/5 stars
Commentful is pretty bad. Despite a nice layout and a fancy yet simple design, the user interface is clumsy and non-intuitive. It requires you to add a title and a time period to track comments. The time period could be useful if you don't care what people are saying after a few days, but besides that I'm very unimpressed.
My rating: 1/5 stars #technology