Expired, croaked, kicked the bucket, or bought the farm – no matter how you look at it, mobile computing solutions such as laptops, smart phones, and netbooks have replaced the once venerable desktop computer.

This isn’t new trend either, laptops have outsold desktops since the third quarter of 2005, and the gap has grown every quarter since.

Why?  Simply put, business is increasingly done on the go.  We are no longer tied to a desk and a land line, we are free to conduct business wherever and whenever we choose, in order to let us be as productive as possible.

One of the only things that are holding us back is our software.  If we have to rely on desktop applications which can only be accessed from one computer or physical location, our productivity is reigned in.

Luckily, there are lots of great web-based applications which aim to replace whichever piece of software is holding you back from untethering, be it Photoshop or Quicken.  Here are ten of the best (free!) web-based software replacements available to help you be as productivity (and mobile) as possible:

Q10 / Writeroom
Replaces: Your word processor of choice
Ever needed to type something out, only to get about two sentences in and then get distracted by some blinking alert on your desktop or somehow end up surfing YouTube for hours instead of working?  It’s happened to the best of us, so minimize distractions with these great word processors (for PC and Mac respectively) which let you do things like type in full screen and setup your display so you can work uninterrupted.  Just think of it as a really, really advanced typewriter.

Dropbox
Replaces: All your USB keys, CDs, or heaven forbid, floppy disks
My favorite application in years, this is the most dead-simple way to store and share your files across multiple systems.  Just install the client on any machine(s) you’d like – be it PC, Mac, or Linux – drop and files you select into the Dropbox folder, and it instantly syncs across all systems.  You can even share specific folders with other Dropbox users, undelete files, and make a viewable online gallery out of your pictures folders.  The bottom line is that if you have an internet connection your files are always within reach.

Aviary
Replaces: Adobe Photoshop and Illustrator
Sometimes you just need to create a graphic, but paint won’t cut it and Adobe software costs an arm and a leg – enter Aviary, the free online graphics editor(s) that gives you all the features necessary to create mind-blowing creations, all you need is an internet browser.  The best part is that Aviary is working towards creating an entire online suite of apps that might one day become your one-stop shop for graphics needs.

AlertThingy
Replaces: The F5 (refresh) key
Silly name, sure, but this is one seriously useful application.  Built on the Adobe Air framework, this RIA (rich internet application) lets you monitor your social networks of choice – be it Twitter, Basecamp, Yammer, Flickr, Digg, or a whole host of others – from a convenient desktop application without having to open your browser and a bunch of tabs.  Also, with a built in filtering system it makes it easy to find the information you want, and save you from the dreaded “information overload”.

Remember The Milk
Replaces: Sticky notes & things written on the back of your hand
Take your tasks with you, and make sure you never forget anything again; that is the promise of this great app.  Offering integration with Gmail, your IM program of choice, or your smart phone (iPhone or Blackberry), you can constantly stay updated on the status of your to-do list and help you get things done.  Because, as we all know, there is nothing more satisfying then crossing a bunch of stuff off your list!

PDF Hammer
Replaces: Adobe Acrobat
Usually a document is finalized, then it is converted to a PDF, but as we all know, there is almost always some minor tweak that needs to change at the last second which involves editing the PDF or recompiling it.  Don’t have a PDF editor?  Don’t sweat it, just fire up PDF Hammer.  This amazing web app lets you edit, combine, secure, and add metadata, to any PDF and then save it back to the system you are on, saving you countless headaches.

280Slides
Replaces: Microsoft PowerPoint or Apple Keynote
Tired of looking at the same old PowerPoint presentation?  Shake things up with 280Slides.  Create stunning presentations right in your browser and view them in full screen, or export them as a PowerPoint file for later use.  You can even upload existing presentations and edit them online or pull in media from the likes of Flickr and YouTube.  It also sports the slickest user interface I have ever had the pleasure of using in a web app, and it will really have you wondering why conventional presentation software can’t be this user-friendly.  I haven’t opened PowerPoint since I found this gem.

Zoho
Replaces: All your productivity software
Zoho offers a full suite of online applications aimed at replacing your normal productivity software like Word or Excel, and offers easy collaboration with other users.  In addition to all the standard fare, they offer specialized apps like invoice creators, project managing software, CRM solutions, and HRIS applications.  It even utilizes single sign-on so you can log into Zoho using your existing Google or Yahoo! accounts.

Mint
Replaces: Quicken, and your traditional online banking
In tough economic times it pays to keep track of every penny, and there is no better way to do that then with Mint.  This web-based personal finance software merges with your bank accounts and keeps track of all your earnings and spending in order to help save you money.  It is akin to having an entire accounting firm at your beck and call.  The only downside is it isn’t available in Canada!  So for now I just get to hear about how great Mint is from my American friends, and hope that Canadian support is coming soon.

Ubiquity
Replaces: Un-needed keystrokes
While not a stand-alone application, this extension for Mozilla Firefox is worth mentioning for the sole purpose of the amount of time it can potentially save you.  Say you want to add a map to an email.  Normally you would have to open Google Maps, find the map and then embed it in an email, but using Ubiquity you can perform this whole task with a single command line in your browser!  In fact, you can do all sorts of cool tricks like search Wikipedia, checking the weather, or sending email all with a single command – check out the full list in the Ubiquity user manual.

Keep in mind that these are only ten of the countless awesome application that exist online which have the potential to boost your productivity.  If you know of any others, feel free to leave a comment!  Who knows, you may be introducing someone to a tool that changes the way they work.