An intuitive Google cache module is something that I haven't come across.
This tool could alert/report when a backlink had been cached for the first time - allowing an SEO manager to monitor any potential impact. This theme could then be widened into a cached backlink count within any set date parameter - split by destination URL, anchor text etc. Also you could illustrate the best performers that are cached most regularly and then URLs within the client's link footprint that haven't been indexed in the date parameter set by the user. Some simple suggestions could then be made to kickstart the 'worst performers'.
In-house SEOs, agency link builders and SEO geeks watch this space.