I've been spending a lot of time on web applications lately, and they are great. In my business, volunteer, and personal lives, I find the range and quality of the offerings to be impressive.
I love Constant Contact for email campaigns. I'm addicted to the reports that you can download. Wearing one of my other hats, as a volunteer for my local Girl Scout service team, I love the Patriot's Trail Girl Scout Council's eCouncil app. (Well, I don't love that it doesn't support Firefox. For that matter, neither does Sovereign Bank's online banking system. Boo). Both Constant Contact and eCouncil allow me to download data into Excel where I can analyze and slice & dice using pivot tables and such.
I also rely on yahoo groups to maintain email lists, links and file libraries for several organizations I help to manage. I also love uploading my photos to Snapfish, sharing them, and letting others pay for their own prints if they want them. I used to order double prints, painstaking label them all and send them off to my family. They probably didn't even want most of them.
The drawback to both of those apps is that the people I'm sharing with are not always web-savvy, or they don't want to have to sign up for something. I find myself doing technical support for them, or I lose them altogether.
Another app I've used but don't have that much use for is business networking site LinkedIn. I've spent my considerable career building up contacts. I'm not sure I want to just give them away. So I will not upload my Outlook contacts file to LinkedIn. I also hesitate to spam people with LinkedIn invitations, so I've taken the approach of only connecting to people who are already in the network.
Finally, I just happily signed up for a Mozy online backup account. Mozy now backs up my data whenever my computer is idle for 30 minutes or more. A few years ago I spent thousands of dollars saving data from a hard drive crash. I never want to go through that again, but setting up a local backup proved to be complicated. A backup that doesn't get run is no backup at all.
So hooray for web apps. Long may they thrive!