<iframe align=center src=http://www.flickr.com/slideShow/index.gne?user_id=12345678@N00&tags=foo frameBorder=0 width=500 scrolling=no height=500></iframe>
Alternatively, you may opt to use standards compliant embed code, although I have heard it does not work as widely as the iframe solution does.
<object type="text/html" data="http://www.flickr.com/slideShow/index.gne?user_id=12345678@N00&tags=foo" width="500" height="500"> </object>
Place this somewhere on your website or within a blog post. Change user_id from 12345678@N00 to your flickr id, which you can find out with this idgettr. Also replace foo with the tags of the photos you wish to display.
Other parameters include the following:
For those wondering how I came up with all of this, it was no more than some determined API investigation. If you want to use one of these extra parameters just add it after your user_id with a separating ampersand (&). Don't forget to subscribe to my RSS feed on your way out. And for those wondering, there is no way to adjust the size of the flash slideshow as it is fixed in size and hosted on flickr. If you are looking for a different type of flickr photo integration, check out Diego's pictobrowser.