Preparing to tackle this Thing, I went off to reread the blog entries of two fellow Thingsters. Both of their embedded slideshows are dead. This isn't inspiring confidence in the Thing 37 toys.
Not quite ready to tackle a slideshow, I started with a mosaic image, using Image Mosaic Generator. Their advice is to stand back from the image about 5 meters to see it at its best. I settled for shrinking it to about 20% of original size. So see Multnomah Falls as made up of dillions of other people's images:
By the way, many of the photos that comprise those yellowish trees on the left are of rubber duckies:
Now ready to put together a slideshow, I started out by trying Animoto through Facebook. I quit after seeing that even though they had 146 reviews, they weren't scoring very high--and it looked like they'd made the reviews disappear. After that, I figured I'd just go for a no frills Flickr slideshow.
Okay, it's not playing music, but I can live with that. Pop music didn't seem to go with all those nature photos anyway.
I wouldn't say the services I tried worked "smoothly." Flickr, which you'd think would be solid and established by now, locked up when I tried to sign in. Animoto was behaving less than trustworthily. Yet I remember ten or fifteen years ago when creating a music video of your photos or video clips was a massive undertaking, done only by the truly dedicated, and now it's a free service that basically just asks for you to do some uploading. I might play around with this more when (if) I have more free time. We did a Flickr tour for our library. I doubt music and fancy transitions would improve it any, but we can always keep the possibility in mind.