InstaSaver : Make Your Own Screensaver
Free online screensaver maker that lets you transform your favorite photos into a full-featured Windows screensaver. Just upload your favorite pictures and InstaSaver will generate a standalone (.exe) application that enables you to easily install / uninstall your screensaver.

Features
- Upload screensaver images either from PC or pull them images from Flickr.
- Image Requirements: .JPG images only / Max. picture size: 512 KB / At most 10 pictures for each screensaver.
- Slideshow settings: Picture slide over (on/off), picture stretch (on/off), specify transition speed, choose custom background, etc.
Check out InstaSaver @ www.instasaver.com



Excellent webapp!
I prefer make my own screensaver rather than download one. And i like to use 2Flyer Screensaver Builder which is the fastest and most powerful tool to make screen saver or slide show presentations in minutes.
http://www.sharewarecheap.com/2Flyer-Screensaver-Builder_software_2112.html