Photo Bucket Embedded Slide shows provides seven styles of embedded slide show. I like this one, but you can view the others here.

Embed a Slide-show

I think this service looks great. But it has disappeared from Flickr and is sometimes "missing" from Picassa accounts! I've asked why on forums and received no reply.

Embed YouTube and Google Video

Embedding video that has been uploaded to YouTube or Google Video works the same way as embedding slide shows. Copy and paste the HTML into the Blog Entry after clicking Edit Html.

PictoBrowser using Flickr

Another way to display photos, this is an online widget which is available to anyone with a Flickr account by clicking the INFO button in the bottom right corner of any PictoBrowser

Link to Picassa Album

This is a more sophisticated way to view photos, as a slide-show embedded into the blog page.

A Simple Photo Post

It's straightforward to post a photo on Blogger and it automatically creates a Picassa account for you.