A page at reuters.com had one last week.
Yep.
Google had to shut down access to a major Ad network just last week (auto-blocked from Chrome), which impacted all sorts of "high profile" sites, including The Verge, The New York Times, The Huffington Post, Los Angeles Times, and The Washington Post. This, too, was due to an ad-network exploit that was found to be serving malware.
I strongly recommend:
1. Uninstall Java entirely if you don't absolutely need it. If you do, remove it from all browsers on your system except one browser that you use only for Java-enabled sites that you need.
2. Use a click-to-play Flash extension like FlashBlock on Firefox, if you have Flash installed.
3. Use an Ad Blocker like AdBlock Plus (again, on Firefox) and whitelist sites that you trust and visit regularly (thereby still preserving the revenue stream for those sites you appreciate, but protecting most of your "regular browsing").
4. Keep your browser (and Flash plugins) up-to-date. Luckily, most modern browsers have made this process MUCH easier. I really like Apple's new direction of just blocking "known bad" plugins at the OS level, actually. Microsoft needs to do the same.