This is the Chrome Add-on I use the most.
I've search the globe, and I've yet to find anything else available that can do what Grackle Docs does... and they are super-responsive to suggestions. These guys are not just doing the low-hanging fruit: they are taking on the heavyweight issues... so every week we're finding the product deals robustly with increasing complex Google Docs. As an accessibility expert who teaches people how to make accessible PDF, I'm a big fan of telling people about Grackle Docs.
I have more to say: see http://www.davidberman.com/grackledocs
... keep up the great work! Keep calm and Grackle on!