I have over the years hade 3-4 websites and email addresses, blogs. I want to find a way to go one place to access all of them.
Use Gmail to import everything into one account. https://support.google.com/mail/answer/21289?hl=en
It's a good idea to keep accounts separate though if they are for different purposes. You can setup filters in Gmail for important emails. I also find it very helpful to use Google Chrome's User Accounts to easily switch between different Google accounts. Feel free to call me at 812-650-4405 if you want to discuss this more.
With Gmail you can also set reply base on which email was sent. So example if they emailed firstname.lastname@example.org you can set to to reply back from that email and not your main Gmail or Google Apps email.
If this is just for your own use, you can create a webpage that has pointers to all your websites, email addresses and blogs. You can create a "dashboard" that gives you one place to access all your important areas.
It doesn't have to be a webpage - an excel spreadsheet or even a word document can accomplish the same thing. The idea is just to create a dashhboard-interface that has all your pointers. It is easy to do.
Once again -- it wasn't clear in your question - if this was merely for your access or for marketing purposes.