GQueues – I was a Toodledo user, then most recently a Producteev user. As there was no native android support I’ve recently switched to GQueues as my task/GTD and general list app. I find Producteev colourful, but a bit sluggish, and the lack of control (eg export) always made me wary of trusting Producteev too much.
GoogleApps – Gmail, iGoogle, GTalk, Calendar with multiple domains for both work and personal life.
Evernote – I tossed up between Springpad, Catch and Evernote and moved between them for a long while. I’m on Linux 99% of the time where Evernote has no native app but their most recent Android app revision and introducing nested folders in their web app has won me over, for now.
Soocial – This is my contact manager and syncs my contacts on my android phone (rather than using the inbuilt Google Contacts, which grabs every contact you’ve ever mailed). It synchronizes contacts across my multiple Google Accounts, Mac and iPad.
Pinboard.in – my bookmark manager catches everything from readitlater list to twitter links to manually bookmarked pages.
That’s 5 apps above, but underpinning everything I do, although it’s not actually a web page I open often as such, is LastPass, the cloud password repository. It is the first browser extension I install on any device, and the foundation service I use to reach the above apps.