Flickr is one of the old ones out there - when everyone was still typing html to make a webpage with images, Flickr emerged and shook our planet. Today they're still very popular, even after they've become part of Yahoo. 123Flickr is a website that will accept your flickr credentials and allows you to create a slideshow you can embed anywhere on the web. Although that sounds like a good plan, I don't get it. Flickr already allows you several types of embedded images thingies for websites - and if you want a nice slideshow I would recommend using Google's Picasaweb. The english language version recently started offering embedded slideshows.