Looking for "Add to Feedly" or "Tweet This Page" in the Chrome Web Store? You won't find them now, as Google has removed them for violating Google's TOS. It just so happens that both extensions were created with code that is also used to set up advertisements. While neither extension had more than 100,000 users, those who had adopted Chrome took to forums to level complaints against the removal.
The Wall Street Journal reports (via TechSpot) that reports from users indicated that when either extension as utilized, pop-ups and spam would spring up out of nowhere. As it turns out, both extensions had been sold to outside parties who sifted in the malicious code. Since Google doesn't check out said code after approval, users were stuck with the frustrating ads as a result.
Are you missing either one of those extensions or are you glad to see they're gone?