I use Soho Notes, and I’m probably not using even a quarter of its capabilities. It has an iPhone app, and if you look at Chronos’ other products, they have some organizer/contact management programs that work w/ Soho Notes.
For about the past 30 years, I have bought a calendar book by Quo Vadis, each week on a pair of facing pages. It is about 3" x 4" and fits neatly into my pocket. Every year, I update and reprint in 8pt type my list of important addresses and phone numbers and glue them into the book. Unfortunately, every year it is harder and harder to find that size. There are larger sizes, but where would I carry them. Of course, I write in all appointments and such and try to look it over at the beginning of each week.
I have thought of having an electronic diary, but it seems like more trouble than it is worth.
I use my brain. Appointments, bill due dates, phone numbers - all in my head. I don’t need to carry a day planner and I’m not at risk of losing my entire contact list to a hard drive failure. I write down the grocery shopping list though.
I use a standard-sized Franklin Covey planner.
A combination of Google Calendar, Gmail, and my cel phone.
Bills and payment schedules and reminders are cc’d from my bank to my Gmail. Calendar will SMS non-bill reminders to my cel phone, in case I’m away from a computer.
It works fairly well, the only flaw is the human one when I procrastinate or conveniently forget to read my email.
I have shopping lists in my iPod Touch. Of course I often forget to consult them.
Immediately needed things I write on post-it notes and carry them with me.
Phone numbers I have in my cell phone, e-mail addresses are in Gmail.
I use Google and my Droid for most things; in fact, the Google integration is the main reason I got a Droid. My Google and Facebook contacts sync, I have a Google Calendar for all of my appointments (the office uses Outlook, but I have so few work appointments that I don’t mind adding them to my Google Calendar as they occur), and I use a Google Docs spreadsheet for my grocery shopping list. For general notes I could also use Google Docs, but instead I use a free Droid app so they’re offline yet always handy. I use Google Docs for lots of other stuff, though: recipes (so nice to be able to refer to those while I’m in the grocery store!), my DVD collection, what movies I’ve seen, etc.
For my budget/bills I still use an Excel spreadsheet (to tell me what’s due when and how much I’m planning to use of each paycheck) and Quicken (to track actual spending). Those are both local to my personal laptop: every now and then I think about moving to online tools for that stuff, but I really have no compelling need to do so yet.