Since upgrading to a 3G iPhone, I’ve gone on periodic app binges in which I download every app that looks remotely interesting and take it for a whirl. So far, the best discover I’ve made is a free app called Evernote — and it’s changed my computer use even more dramatically than it’s affected the way I use my iPhone.

Evernote is a notetaking application that lets you take notes on your computer (Mac or Windows) and keep those notes synced with your iPhone and the Evernote web site. Any note that you take on your iPhone gets synced back to Evernote, too. You can keep multiple notebooks (e.g. one for draft blog posts, one for grocery lists, and one for each client project) and choose to keep some or all of these notebooks local (just on your computer) or online (synced by Evernote). While you can keep as many notes and notebooks as you want on your local computer, the free version of Evernote limits data uploads (i.e. syncing) to 40 MB a month. But it only costs $5 per month to get an account entitling you to 500 MB of data uploads, which Evernote says is enough to hold thousands of typed notes, five thousand snapshots, or 450 audio notes.

The Evernote interfaceEvernote interface

That’s right: audio notes and snapshots. Use Evernote to capture audio notes on your iPhone and they’ll automatically sync to Evernote on the web and on your computer — no waiting for your next iPhone sync. Use Evernote to hold your iPhone snapshots and they’re synced, too.

And since Evernote features optical character recognition (OCR), any text you snap with your phone (or another camera whose contents you drop into Evernote) becomes searchable. For those of us who are whiteboard-dependent, that means you can now capture your whiteboard notes and they’ll be searchable! Ditto for business cards, flip charts, signs — whatever you care to shoot. (OCR only works on notes that have been uploaded to the web, so if you want your images to be text-searchable, you’ll need to put them in a notebook you keep synced online.

The Evernote interface makes it very easy switch between notebooks, and to move notes back and forth among them. You can tag any note with as many keywords as you want, so that provides a further layer of categorization.  In other words, it’s a terrifically easy, flexible and powerful way to take notes on your computer or iPhone, and keep them in sync. (NB that you can’t edit pre-existing notes on your iPhone, however, including those you created on your phone; and it would be MUCH easier to take notes on the iPhone if Evernote let you rotate the phone to use the wider version of the iPhone keyboard.)

If you install the Firefox clipper extension (or the “clip to Evernote” bookmarklet in any browser), you can use Evernote to store and tag your favourite web clippings, too. Unlike this lets you stash the actual web page (or highlights) rather than just the URL and description. Unlike there’s no sharing feature, however, so it’s not a substitute if you like the social in social bookmarking. (I’m hoping some clever person will hack together a tool for saving a web clipping to Evernote and simultaneously, or keeping web clippings synchronized between the two.)

One social thing you CAN do with Evernote is to share a notebook, and optionally publish it as a widget on your blog or webpage. I’ve created a little notebook of web clippings about how to use Evernote, and set it up as a shared notebook, which you can see here. Once you make a notebook public you can add it to a Facebook page, or to your blog, as a widget that looks like this (click on any box to open that note; you’ll need pop-ups enabled): (NOTE: I think Evernote has discontinued support for this function.)

Evernote’s interface, syncing and clipping features make it a very tempting choice as a primary notetaking application. For the past three years I’ve been a devoted user of Voodoopad, and it’s painful to think about giving it up — not just because the migration process will be a bit arduous (see below) but because of how much I’ve loved VDP. It’s hard to think of an application that’s had a more profound impact on my work habits: where my notes used to be scattered across an assortment of paper notebooks (remember those?), Word docs, text files and scraps of paper, just about every thought, phone message, meeting record and blog post I’ve written in the past three years is captured in one of a dozen Voodoopad notebook. (I use one for each major client or project, plus a catch-all file.) Vooodoopad makes it a snap to keep and retrieve notes, and its creator, Gus Mueller, is the most responsive developer I’ve ever encountered.

But the iPhone syncing and the Evernote interface are significant advantages. Since I routinely use about a dozen different Voodoopad notebooks, I end up with a lot of open windows. In Evernote it’s much easier to switch between notebooks. Also I really like being able to sort a notebook’s contents by date — something that I still can’t do in Voodoopad.

On the other hand Voodoopad has one MAJOR advantage over Evernote: data import and export. Right now there’s no easy way for a Mac user to get data in or out of Evernote.  The Windows client offers an option to import databases, export a note or notebook to HTML. (Both Mac and Windows users can send notes by e-mail.)  While Evernote suggests that export might become available to Mac users in the future, for now the only exit path is via Windows. That makes switching TO Evernote a big pain (I’ll have to export my Voodoopads, then run Evernote on Windows in Parallels to get the data in….and why does that sound like a nightmare?) and switching to a future app just as annoying.

The wishlist item that would make Evernote REALLY rock out — or convince me to stick with Voodoopad — is if either program offered Google Doc- or SubEthaEdit-like collaboration. (SubEthaEdit is a 100% real-time collaborative editing program that’s great for writing documents, code or note-taking with your colleagues.)

I’d love to have collaborative notebooks on Evernote, in which I invite a designated set of colleagues to access and/or contribute to a notebook. In an ideal world this would include complex permissions options so that I could designate any synced notebook as “publish only” (make all notes in this notebook visible to the people I’m inviting), “publish or contribute” (my invitees can add their own pages to the notebook as well as viewing mine), or “publish, contribute and edit” (invitees can view pages, add pages, or edit existing pages). In my super fantasy scenario you could also turn on live collaboration for any note you’re currently editing, so that you can do live collaborative notetaking the way you can with SubEthaEdit.

I’m not sure whether collaboration is in the cards for Evernote, but I’m hopeful. It’s clearly a feature-rich program with lots of bells and whistles I’ve only begun to explore. For example, it was only in researching this post that I discovered Evernote will sort notes I create on my iPhone according to where I was when I created them. If I create a notebook of restaurant notes I’ll be able to find all restaurants I’ve visited within 1 mi of my current location.

I’d love to hear from other folks about their experiences with Evernote, and particularly about any neat features I may not have discovered. And if you’ve tried both Evernote and Voodoopad, which one have you landed on?