The Google Webmaster blog has a post today about how to develop search engine friendly sites, even though they use Ajax.
Note that the static link's URL has a parameter (?foo=32) instead of a fragment (#foo=32), which is used by the Ajax code. This is important, as search engines understand URL parameters but often ignore fragments.
Basically, the code fragment above presents a static link to the search engine, but still follows your desired Ajax path through the use of the onClick function.
Our own advice to people who want to build tools, or have other interesting uses for Ajax, is that it's a great thing to do. In the increasingly social web, usability and site experience is playing a bigger and bigger role in driving traffic, and yes, in driving links to the site.
Don't be afraid to leap in and create such tools. Just make sure you still leave a trail that the crawler can follow.