Jalbum is extremely easy. You select a style, point it to a folder and it generates an album with slide-show capabilities for you. All you have to do after it to upload it to a server somewhere. Do check out their website, it illustrates things pretty well.
Adobe's Photoshop Lightroom can also create both HTML and Flash slide-shows from pretty much any set of images it already manages. Same as Jalbum, all you have to do is to upload it somewhere. Of course, if you do not use it already, it is seriously overkill.
The nice thing is that since a couple of versions, Lightroom can also upload to one of those sharing sites, including Facebook, Flicker and Smugmug. Personnally I never used these features but I cannot imagine them being hard to use.