Two large online health information companies, Waterfront Media and Revolution Health have agreed to a $300 million merger that threatens the sector’s dominant player, WebMD.

Brooklyn-based Waterfront Media was formed in 2002. It operates consumer health sites including EverydayHealth.com, WhatToExpect.com and SouthBeachDiet.com. It is believed to turn a profit on revenues of $50 million. Washington D.C.-based Revolution Health was founded last year. Its consumer health sites include RevolutionHealth.com, CarePages.com and HealthTalk.com.

According to comScore, WebMD had 17.3 million unique visitors in July, 2008, the highest traffic in the space. That same month, EverydayHealth.com had 14.7 million visitors and the Revolution health sites had 11.3 million, good for second and third place overall.

The newly combined entity is projecting more than 20 million unique users and more than 3 billion page views per year. A Waterfront press release suggests the new entity will offer advertisers a “unique opportunity to target consumers across the entire spectrum of online health and wellness.”

Waterfront’s co-founder and CEO Benjamin Wolin will run the new entity, while Revolution Health’s CEO and Chairman Steve Case joins its board.

Before starting Revolution Health, Mr. Case co-founded AOL which merged with Time Warner at the peak of the Internet bubble. Time Warner now wants to dump AOL, which has been hurt by declining advertising revenue.

WebMD is also expanding. It recently announced plans to acquire QualityHealth.com for $50 million.

Last week, the US Postal Service and its major labor union tentatively approved HHS Secretary Mike Leavitt’s proposal to have mailmen distribute doxycycline to all homes along their routes in the event of an anthrax attack.

“We have found letter carriers to be the federal government’s quickest and surest way of getting pills to whole communities,” Leavitt told the Washington Post.

Mail carriers would not be required to participate in the distribution scheme. Volunteer mail carriers would be accompanied by police officers during any handout.

HHS has conducted trials of the proposed strategy in Seattle, Boston and Philadelphia. In one trial, 50 carriers delivered antibiotics to 55,000 homes in less than 8 hours. Now the plan is to run a more extensive trial in the Minneapolis area.

One small problem is that the FDA has not approved doxycycline for the treatment of anthrax. Leavitt requested an expedited review last Friday. Take a number, Mike.

Census Bureau data reveal that during the recent economic expansion, workers with professional degrees (e.g. physicians, lawyers) were the only educational group to see an increase in inflation-adjusted income. Every other group from Ph.D.s to high school dropouts experienced declining income.

In 2007 for example, professionals had an inflation adjusted median salary of $89,602, a 3% increase from 2000. In 2007, people with bachelor’s degrees earned $47,240 and high school graduates earned $28,290, respectively-a 3% drop for both groups during the period.

At least the data suggest there’s value to higher education. Master’s prepared people earned 20% more than those with bachelor’s degrees, and they in turn earned 67% more than those with high school diplomas.

These differences are shrinking though. In 2000 workers with a college degree earned twice as much as workers with high school diplomas. So when are those college loans due anyway?