this post to the Google Blog discusses Google's accessibility efforts and commitments. I use my Google Calendar to manage my life. I set my appointments using my voice by calling , "Dial-To-Do." and putting appointments on google calendar. My assistant Michelle adds appointments for me. I can add appointments directly out of Outlook, since my Outlook and Google Calendar synch and so do my iPhone and google calendar.
Way to go Google.
Official Google Blog: Enhanced accessibility in Docs, Sites and Calendar