[This post is just my random thoughts on Blogger hacks and features. I have read some such posts elsewhere, so I thought I will write one too!]
One of the ideas for a nice hack could be "comment threading". Instead of the flat list of comments, what if we have a forum-like threading of comments? For example, say Tom comments in my blog and I reply to his comment. Then, my reply should appear right below Tom's comment (a little indented though). If Tom replies back, it should appear below my comment, even if he replies after several others comment. This will help in organizing comments into multiple threads and makes it easy to follow the thread that you are interested in. What do you think about this?
I think post summary feature should be built into Blogger. I mean Blogger itself should allow users to type summary and full post in different textboxes thereby recognizing them differently. If this is supported, then we don't need to use the special post template for expandable post summaries. Ofcourse, they don't need to support peekaboo posts but they could show the summary alone in main page and provide a Read more link to goto the post page (if there's no summary, then they could show the entire post). This will also come handy in deciding where to stop in summary feeds. Right now, Blogger goes by number of characters and summary feed stops abruptly in the middle of a sentence!