I have been using Gmail for quite some time. One thing I like best of Gmail is the nifty keyboard shortcuts. It is one of the reason I prefer Gmail to Yahoo mail. Actually, I even prefer Gmail to native email clients on local machines. The internet application mode is much more superior.
From various sites you can read a list of Gmail keyboard shortcuts, but I just dug out the undocumented delete keyboard shortcut: shift+#. It is quite handy.
Last week, I tested out the Good Reader, very nice news feed reader. Also, it has a complete set of keyboard shortcuts. I like the g+u+feed combinations very much. The j, k, n, l, keys are second nature to me.
My cell phone is a Motorola SLVR L7, which is SyncML enabled. Yesterday, I discovered Goosync, which you can easily synchronize your phone calendar with Google Calendar without using a computer, everything goes through WAP connection via SyncML. I tested it out, it is very useful. A similar site is GSMSync. GSMSync can even synchronize my phone book, even better than Goosync.