So what do you do?
You can, of course, create a new Google account there and then, to house your Blog, your Calendar, your YouTube Channel - whatever it is you are wanting to sign up to. But if you do that with every Google product you want to use, you will pretty soon build up an entire arsenal of different Google accounts, each with their own username and password, and each of which links to only one product you actually use. Confusing? You bet.
What's the alternative?
Do you already have a Google account? If you use any Google product at all - Gmail? YouTube? Blogger? Drive? Calendar? - then you already have a Google account, alive and kicking and ready to use.
If you do, and you would like to use your new Google product with that same Google account, then first, just sign in to the account with your usual username and password. Then revisit the new service you want to use. Go through any sign-up procedure required (sometimes none are required at all!) and that new service will seamlessly be added to your existing Google account.
That helps you to keep a single Google account for all your Google services, instead of having several independent Google accounts scattered all over the place, each with a different product attached to it.
How does this work?
Well, a Google account is more than just an "account". It's a kind of portal. The intention is to give you a single sign in - just one username and password - which then enables you to use the whole range of Google products to store, publish, share and manipulate all your information.
Try it - sign in to any of your Google accounts, and flip through the Apps in your App Switcher icon and the More menu. You'll find Google+, Maps, YouTube, Drive, Calendar - as you visit each one, you'll see if you look up to the upper right that you are actually already signed in to all of them, even if you haven't yet used them with this particular Google account.
So - having seen that you CAN use one Google account to sign in to all your Google products and services, what can you do tidy up all your existing accounts?
How to consolidate
Some products simply can't be moved to another account.
Gmail is one of those, because if you use Gmail with a Google account, it's the Gmail username and password that provides the unique identity for that Google account.
If you could move it in any automated way, then that Google account would lose its identity - so that's a no-no - but worse, the Gmail address would have to change when added to the account it was moving to - another no-no.
So unless you are prepared to sacrifice your existing Gmail address altogether, and set up a new Gmail address within another Google account which doesn't yet use Gmail (see below for how to do that), you can't shift your Gmail lock-stock-and-barrel to another account.
But many other products CAN be moved, or shared, or you can use some judicious export-import techniques to move the data manually.
For example, a Blogger account can be moved simply by changing the main "author". Add a new one, and then remove the original one. If your blog contains uploaded photos, you may need to move them too (see below) or leave the old account alive, even if otherwise unused.
For your photos uploaded directly or via Blogger to Picasa Web Albums (and viewable in Google+ as Photos) you can take advantage of a one-off migration service - and if you do that as well as moving your blog (see above), then you can eventually delete the original Blogger account, as the photos in the blog will also have moved to the new account.
A Calendar can be moved by exporting it from its original Google account as an ICS file and importing it into a new Google account. Or if you aren't deleting the original account, you can just share it with the new account.
Contacts can also easily be moved between accounts using the export-import route.
A YouTube channel can be sometimes be migrated to a new Google account - provided it was created prior to May 2009. If you don't have the migration option, you could choose to download your content and re-upload it to a new account - tedious if you have a lot of content, but useful as a last resort if you really want to delete the Google account that houses your YouTube channel.
Google Drive documents can be downloaded (and if you use Google Drive Sync, you already have the files stored on your computer) and uploaded to a fresh account. Or you can transfer ownership of documents you want to keep to another account.
If you have an AdSense account, you can also move that.
First make your plan
To help you plan your consolidation, and work out what you can migrate to where, there's a full rundown of what can be moved and what can't here:
It's also a good idea while planning to visit the various Help Forums for each product and consult with the expert users who help out there, to ask advice and sometimes get very specific additional instructions.
And the Data Liberation Front website gives masses more information about "escaping" to and from multiple Google products and explains the Google Takeout service.
You may not be able to rationalise all the way down to one account - as some products simply can't be moved. But you can at least reduce the number of active accounts you need to use to access all your services - if nothing else, that's fewer usernames and passwords to remember!
Finally - housekeep!
Take it slowly, move one product at a time, exercise patience and accept the limitations - then your consolidation should rationalise your account usage and make your life a great deal easier in future!
NB - for a full and detailed explanation of the ins and outs of Google accounts, visit the first post in this blog here: Google Accounts - how they work
PS - moving Gmail data to a new Gmail account
So you've decided you want to get rid of an existing Gmail account - or perhaps more than one! - and create a new one inside another of your Google accounts. Or maybe you just want to consolidate several Gmail accounts into one, and delete the ones you no longer need.
Once you've created your new account under the umbrella of an existing Google account, or picked the existing account you want to make into your main Gmail account, you need to start transferring your Gmail data.
For your messages you can either use Mailfetcher - find that here:
Or if you are concerned to keep all your labels, you can use a backup/restore solution like Got Your Back - find that here: http://code.google.com/p/got-your-back/
Other backup/restore solutions are here: http://gmail-tips.blogspot.co.uk/2012/01/gmail-backup.html
A third way to move your mail is to set up both old and new accounts in an email client like Thunderbird, using IMAP connections. When both accounts are synchronised with the client, you can copy your mail from the old account to the new account in small batches. Though I don't recommend you try this solution unless you are familiar with and comfortable using IMAP with email clients.
For your contacts, you need to export from the old account and import into the new account:
Filters can also be exported and imported: go to Settings/Filters to do that
* Gmail is a trademark of Google, Inc. This page is not sponsored by or affiliated with Google.