Here is a new utility web page to easily create javascript: bookmarks (bookmarklets) that paste a custom text string into a web page form in Mobile Safari on iPhone or iPod Touch– http://mobilemind.net/iphone.

On iPhone and Touch, that page will automatically re-direct to http://mobilemind.net/___, which includes all the instructions and code needed to make a bookmarklet that pastes text (an “iPastelet”).
Save an iPastelet (thumbnail)
On the iPhone/Touch, Save an iPastelet provides a form to enter your text string and a button to update the page URL. Then you need to save the bookmark, then immediately edit it to remove the http:// prefix and mobilemind URL. The directions on the page explain it all.

On desktop machines, the page does not re-direct, but instead takes you to the “classic” iPastelet Maker that I posted last December. The desktop browser version of iPasteletMaker creates a bookmarklet for you to save in your desktop browser (Mac or Win) and then sync to your device via iTunes.
iPastelet Maker(thumbnail)
This approach might be a little more handy if you already sync broswer bookmarks and want to create a bookmark Scrapbook folder with lots of these.

Thanks to Erica Sadun for the original bookmarklet code and inspiration. Special Thanks to Craig Hockenberry (IconFactory / Twitterific, Twitterific for iPhone), Joe Maller (Transmogrify), Joe Hewitt and the iUI team (http://code.google.com/p/iui/), and Ankur Kothari (Make the most of the iPhone SDK) for inspiration and examples.