Since Apple released iPhone firmware 1.1.3, various people have posted bookmarklets which allow you to add your own icons for any site to your iPhone/Touch home screen. The one which I found worked most effectively I got from iclypso which also hosts a number of user submitted icons for sites which don’t already have there own webclip icon. However, that site (nor any other site I could find from a quick search) does not have icons for some sites which I definitely wanted to have on my home screen. Google and Backpack do not have webclip icons, and Toodledo and Meebo have really bad ones. So I have whipped up my own webclip icons for these sites. The Google, Backpack and Meebo icons use the logos from those sites. The Toodledo icon is just a generic to-do list icon, which could be used for any to-do list app (I never have liked the Toodledo site design). I have also included the icon that I created for my Edinburgh bus timetable iPhone app, but again, it could be used with any bus timetable site.
To use these icons, simply use any of the bookmarklets that allow you to set your own webclip icon for a site (I recommend the one at iclypso) and enter the address which corresponds to the icon you wish to use.