http://www.BannerGenerator.org let's you make over 40,000
styles of banners (over 1,000 image designs)! Make them
online VIA web based image editing applications that run
off a website (no software install required). Easy to download
your creations in *.JPG format ready to be used on your sites/blogs

http://www.SignGenerator.org let's you make free JPEG label
images for your site. A neat sample is the WEB AWARD
GENERATOR on http://www.signgenerator.org/web-award.asp
where you make your own web awards or you could design some
fake safety signs!

http://www.ButtonGenerator.org will let you make some buttons
for your website.

http://www.CustomSignGenerator.com allows you to create
customized funny ecards in flash format. Also a button maker...
Check out the links page for more image tools online!