Keyword & Competition Research
Money Site & Private Blog Network Hosting
Website & Backlink Analysis
I primarily use Moz when I want to see what a websites backlink profile looks like, including my own websites. You can sign up to use it for free, but it has daily limits to how much info you can grab. Highly useful.
When I want to view the historical information of a domain, this is the tool I use. I can find out what the domain used to be, how it looked, if it transferred ownership and more highly useful data.
WordPress Theme & Design Builder
Email marketing software with a ton of incredible integrations and features. I've once again used many in my career and have been extremely fond of Mailerlite and they continue to get better.
I hate writing my own content. So for less than a burger and fries, you can have any article you wish written for you. Reject it as many times as you like if it's not right and it costs the same. You can also have ebooks written! Awesome service for content creation.
Traffic & Stats
I love this stat tracking service. I personally prefer these guys to Google Analytics for a few reasons. They have a more user-friendly interface, and they don't steal/spy on you like Google does! Free for as many sites as you like, or upgrade for more stats!
Want to surf the internet or search Google without them knowing it's you? Want to appear as if you are surfing from Russia, Japan or Australia? This is the tool to do it with. Great for when you are using Magic Submitter or trying to hide what you are really doing from Google. And it's fairly cheap!