I have been trying to break myself from using desktop client programs where possible. I have 4 computers that I use reguarly and keeping track of documents and email across 4 different mail clients just became too difficult. I really miss the functionality and clean interface of Thunderbird and still run it on my home PC just to save and index my email for future reference.
The thing I miss most about having moved away from desktop clients is the ability to add new apps and plug-ins. For example, I use a number of tools to keep my address book up-to-date. Unfortunately, none of these tools offer a handy way for me to synchronize my Yahoo! or Gmail contacts. What I really want is a web-based contact synchronization service that will synchronize with a web-based email program. Right now I have to do manually import my entire conttacts folder from time to time and that really is a poor way to do it.
I can only hope that all of the energy being directed at fixing email inboxes will spill over to other things. We have lots of calendar companies and email interface companies — what about contacts?
Yes, I am aware of Plaxo, GoodContacts, and Accucard (note: I have friends who work at Plaxo and I lfind it useful; clearly not everyone is pleased with how the product works). They all have their fans and detractors and seem to work okay. I am just waiting for someone to solve the synchronization problem for me as I move to a more web-only world.