So now you want one for your own blog, right? Well, it is really easy to do but required a lot of Googling about on my part to find the answer to the various questions as to how to get the thing to actually work :) This post will give you the information you should need -providing your blog is hosted on the Blogger.com platform. I'm sure other platforms have similar abilities but I cannot help with those.
For clarity -what I am aiming to do here is enable a slideshow of just images that I have published on this blog (there are other options to have a slideshow from your Flickr etc albums -but that is not covered here).
Start by clicking on Design on your Blogger dashboard then on Layout (on the left hand side). You will now have a template showing the various current elements of your blog -Blog Posts/About Me/Links etc. What you need is an unused box that says Add A Gadget. If there isn't one where you wish your slideshow to appear you can move an existing element to a different position by deleting then re-adding elsewhere or just using Drag and Drop to reposition an empty box (depends on the technology you are using).
You now have an empty Add A Gadget box in the correct position. Just click on the Add A Gadget words to get a pop up box showing all the various elements you can add. Scroll down and click on Slideshow by Blogger. Now the fun part. First give your Slideshow a title (just type into the top box). Next choose your image source for the Slideshow. The default one shown is Picasa Web Album. Great you will think -that's where the images on my blog are stored so that's perfect. Wrong -you will just get other peoples (public) images from across the whole of Picasa. That might actually suit some and you can fine tune it by choosing a keyword like Sunsets -so you will get a nice slideshow of other peoples Sunsets!
To get your own images use the drop down menu on Image Source and choose the Other option. A new box will appear saying Feed URL (essentially the internet address from where you want your images to come from). Here I tried putting in the web address of this blog -but that didn't work at all. What you need is the web address (URL) of the RSS feed of the appropriate Picasa album. Keeping up?
The easiest way (for me) was just to click on New Post and then the Add Image link. This gives you options to source an image by either uploading or from your existing Picasa album. Choose the latter and then, in my case, the sub-album entitled My Small Greek Islands. On the right you will see a link for the RSS feed for this album. Click this and the address you now see in the address bar at the top is the one you need to copy and paste for your slideshow source.
So, go back and paste this in the Feed URL box and you should start to see a preview of your slideshow appear at the bottom of the pop up box. Success! Now there are just two more boxes to complete. Choose a speed for your slideshow Slow/Medium/Fast and Randomise images (presumably if you do not tick the latter it will just display your images in the same sequence every time).
Finally (!) just click Save at the bottom of the pop up box and then Save Arrangement on your full Layout page. Now go to View Blog to start enjoying your new feature. One thing I did find was that it displayed perfectly on Google Chrome but on IE9 it just kept saying "loading" where my slideshow should be. Worse, my views counter had also vanished from view. More Googling later and I found the solution was to click the Compatability box in the address bar at the top (the little oblong box on the right with a zigzag line through it). Because IE9 is getting old as a system you just need to click this to make the slideshow work perfectly -and my views counter came back as well.
This probaly all sounds way more complicated than it actually is but with the steps listed above you could probaly have your slideshow added and running within a couple of minutes. Enjoy! Regards, David.