I used Tungle to let people see my availability and suggest times for briefings or other events. In the weeks leading up to a major conference like Interop or VMworld, I'm inundated with emails asking to get on my schedule. With Tungle I could reply with an "Yes I'd be happy to meet you, please see the Tungle link and suggest times." I would then get an email, agree to a time and place, and the appointment would be booked without the need for either party to send multiple emails back and forth.
Tungle was also a big step up from publishing my availability in Google Calendar and having people send emails or Outlook invitations. And because Tungle synced with my Outlook and Google calendars, I could keep using Outlook to manage my calendar.
RIM, which purchased Tungle in 2011, announced in September it was closing Tungle so the Tungle team could work on advancements to the BlackBerry calendar. The Tungle team recommended switching to Doodle, but Doodle lacks some key Tungle features, such as an easy way to define the work day for availability.
Back in 2010 I faced a similar problem with Xmarks, a bookmark syncing service. However, rather than just closing its doors, Xmarks appealed to the users of its free service and got enough of us to pledge to pay a few dollars a year to make it attractive to the folks at Lastpass. I'm now happy to pay $20 a year for my premium subscription to Xmarks and Lastpass.
Could RIM have switched Tungle to a freemium model and made a few bucks? I don't know. Just how many free users would have converted and how much that would have slowed BlackBerry developments are open questions. I do know the whole thing has made me less likely to trust that RIM will support any product or service I get from it, and has therefore made me less likely to recommend RIM products.
Of course, with both Tungle and Xmarks my exposure was just the loss of a valuable service. Because I was using these services to sync data with my local Outlook calendar and browser's bookmarks, I could still access all my data even without the services. That's not the case with larger SaaS deployments. Users of more sophisticated SaaS applications like CRM risk more serious disruptions.
Organizations that use SaaS for mission-critical applications have to take steps to mitigate either the probability of or damage caused by the application of their choice going away. You can reduce the probability of your application disappearing by sticking to larger SaaS players, like Salesforce.com or Intuit. You should also make sure that the applications you use are core to your provider's existence. Some providers, like Google, will kill off what they consider unsuccessful apps that are peripheral to their main business.
To reduce the impact of a provider or service shutting its doors, make sure that you can at least export the most valuable data in a standard format, such as .CSV, so that you can use the data when the SaaS app goes away. Losing a valuable application is a major annoyance, but you have to make sure you don't lose the data--that's where the real value lives.
My experience with Tungle hasn't soured me on SaaS. It's the only way a micro-enterprise like DeepStorage can have sophisticated applications like online scheduling and CRM. I spent two or three days looking at replacements for Tungle; after trying several alternatives, I'm now testing ScheduleOnce. The time spent looking was worth it, because having a good scheduling app saves me two to three hours a week of playing schedule tag. As long as I get a couple of years out of ScheduleOnce, I'll be ahead of the game.