If there is single gripe I have regarding the Google system, is that the software developers have made it difficult, if not impossible, to consolidate user data into a single Google Account.
I have multiple Google Accounts — some associated with a Gmail address and others that are linked to a non-Google system. Besides Gmail, I actively use other Google services such as Google Analytics, FeedBurner, YouTube, and AdSense. Unfortunately, I opened many of them under different account IDs. As described on Google’s help page (link provided below), only selected data can be transferred between accounts, which cannot be merged into a single account.