Those are products/services that I am actually using on and my other sites:

Make money online:

When you are writing a blog post, you can display eBay listings related to your content thus earn commission money on every visitor that may decide to buy an item. While other eBay WordPess plugins(free/paid) are available, this plugin has been around since 2007.
phpBay Pro (WP plugin since 2007) use coupon code saveme20 to save 20%

The site has adsharing enable thus you can display an affiliate offer related to your blog.
Afilliate network

To earn money and to outsource work:

Those services are perfect to buy and offer your services to or buy from others.
Microjob (small work)
Outsource (bigger work)

Services and others:

Writing service
Auto responder
Backlinks software
Comments (WP plugin)
Convert words to links (WP plugin)
Domain name
File Manager/FTP software
Keyword research
Payment processor
Scarcity (WP plugin)
Script to sell reports
Spinner software

Note: Most have my affiliate links. I gave generic names in case one them should close/cease to work thus I will have to replace it with an alternative for my own need too.

Consider your budget because your expenses will add up fast. You can start with free ways but from my experience, I started to make more money when I invested money using domains and tools.