SteemPeak

• You can vote on proposals in an easy to use interface @ https://steempeak.com/me/proposals that affect how funds are spent.
• You can schedule posts.
• You can save and store snippets for quick easy access. Great for signatures and other re-usable/frequently used content.

SteemWorld

• You can view your curation effiency. I feel like not many people know about this feature. It essentially tells you how efficient your curation/curation rewards are.