Google Calendar is, like GMail, much loved by users who use it. There is really nothing wrong with the product, but it is a product which works very closely with email (you receive invitations typically via email) so if you are not going to use GMail, you can look at the calendar product attached to the email program of your choice be it, Hotmail Calendar with Hotmail, Yahoo! Calendar with Yahoo! Mail or Exchange Calendar with Office 365.
Hotmail Calendar, when your Live ID is linked to Facebook, has a distinct advantage over GMail Calendar in that it populates Facebook events in your calendar, including birthdays. I find this feature very helpful and is in fact one of the reasons I started using Hotmail Calendar more than my Exchange (Office 365) Calendar. Hotmail Calendar also has the capability to capture To-Do’s which also get sync-ed with mobile phones via Exchange Active Sync, so it becomes a pretty good replacement for GMail Calendar in all respects.
Google Docs is a very hot product suite both in terms of apparent adoption, but also in terms of competing against Google’s arch rival Microsoft. Google Docs include Documents, Spreadsheets, Presentations, Drawings, and a neat feature, Forms. The Docs team has also been very busy adding features to the various products in the suite. Collaboration runs in the blood of the product suite. So why would you want to look elsewhere? First, after Google discontinued Google Gears, there is no way for Google Docs to be edited when disconnected from the internet. Yes, HTML5-based offline storage mode is coming soon, but until then, it is useless without the internet. Second, if you use Microsoft Office on the desktop, and use advanced formatting in your documents, there is a chance you will lose the fidelity of the document as you move from desktop to the cloud and back.
The biggest competitor for Google Docs is Microsoft’s Office Web Apps. Office Web Apps are the online versions of Word, Excel and PowerPoint which, per Microsoft’s claims, preserve the fidelity on the round tripthat is desktop to cloud and back. Office Web Apps are also free like Google Docs, and they are neatly integrated into Hotmail, Facebook (via docs.com) and Windows Phone. Office 365 also includes Office Web Apps for free. Combined with the desktop versions of Excel, Word and PowerPoint, Office Web Apps are a much better set of productivity apps than Google Docs, especially if you are going to work on your documents offline and even more so if you work with Microsoft Office.
Apple has been ramping up their iWork suite as well and they are cloud-enabling their products. I have not personally used these products, but presumably, if you use Pages, Numbers or Keynote on your Mac, you could make iWork work just like Microsoft Office works with Office Web Apps. The downside, at least for now, is a lot of people use Microsoft Office and there is potential for loss of fidelity going from Microsoft Office to iWork just like there is when you open a Microsoft Office doc with Google Docs and make the round tripfrom the web to the desktop and back.
I have been using Office Web Apps since it launched and am quite happy with the suite. I only hope the team iterates faster (we have seen some updates but not at a pace Google Docs releases updates).
Update: Just saw this Computerworld piece comparing Google Docs, Office 365 and Zoho. Thought it would give some perspective.