You can have comments (moderated or not) integrated into your Tumblr by using Disqus.com, as they themselves suggest. Actually, I learned this through you, as you can read here. I’ve really found this option perfect!

As for embedding, you’re allowed to either upload or link to a photo (image), audio or video file. You may also may use of kwot to embed a small screencast of any webpage you’d like to embed, even with active links.

Something else I like about Tumblr is that you can get RSS for posts from up to 5 different sites (which should display YOUR content) automatically integrated into your tumblelog. Great way to create a common showcase for different classes, or teams!

Hope I’ve not misunderstood you and am talking nonsense!

Love,
Gladys
Visit my Tumblr!

You’ve made me a fan of Tumblr, you know!

I’m one of the founders of Soup.io. Thanks for listing our site here, I’m glad you find it useful!

I was wondering what exactly you mean by “it doesn’t appear to me that you can embed anything into them”. What kinds of content were you thinking of?
It’s easy to embed things like images from other online sources (Post image: “copy from website”), videos hosted on YouTube (just copy the embed code or use the bookmarklet), etc. You can also upload any file for download by others (content type File) or automatically import what you’re uploading elsewhere (say, bookmarks with a certain del.icio.us tag, photos from a certain Flickr account, or just any random RSS feed).
Maybe some of these features are too hidden in our interface, or you’re thinking of a totally different kind of embedding: either way, I’d love to know more!

Cheers again for the link.