Few investors consider TV advertisements as credible sources of financial advice or economic analysis. But spending on marketing reveals much about the health of the US economy. At a time when many pundits continue to bemoan the US consumer’s weakened state, advertisers have a refreshingly bullish outlook on domestic demand.

During last year’s “upfronts”–events where the press and major advertisers preview fall programming lineups–broadcast and cable networks locked in more than $16 billion worth of advertising commitments, a 20 percent increase from 2009. Ad rates at every major network increased 5 to 10 percent from year-ago levels. Meanwhile, changes in rules governing spending on political ads have also provided a welcome boost. Rising demand has made it increasingly difficult–and expensive–for advertisers of all stripes to secure prime slots during hit TV shows.

Meanwhile, prices in the so-called “scatter” market, where ad time is purchased on an on-demand basis, have jumped 30 to 50 percent at almost every network. With the US economy picking up steam and consumers beginning to open their wallets, advertisers are jockeying to get their products in front of TV audiences.

Robust demand and seasonal strength should translate into a fourth-quarter bonanza for TV networks, several of which have yet to report year-end results. Here are three of our top plays on the uptick in marketing activity.

Happy Media

CBS Corp (NYSE: CBS) has no problem attracting advertising dollars. The company’s program lineup topped the ratings during the first five weeks of the fall season and attracts a diversified audience that includes young and old viewers of both sexes.

Attractive viewer demographics and the ongoing economic recovery ensured that the network sold the bulk of its available slots during its fall upfront. With limited space for on-demand sales, media buyers report that CBS’ scatter prices jumped by roughly one-third in the fourth quarter.

Data from Nielsen Media Research found that for the period of Sept. 20, 2010, to Feb. 6, 2011, CBS Television Network held the No. 1 primetime ratings for total viewers and for viewers aged 25 to 54.

Full-year earnings should also receive a boost from the divestment of radio stations and other chronically underperforming assets. Not only does this effort cut costs, but management can also redeploy resources from these operations into its higher-growth interactive businesses.

Those divestitures and 18 percent growth in the local-broadcasting division boosted full-year revenue by 8 percent to $14.1 billion. Local-advertising sales were robust and total advertising sales increased by 12 percent.

That being said, publishing arm Simon & Schuster (10 percent of 2010 revenue) and the company’s outdoor-advertising division (12.9 percent of 2010 revenue) continue to benefit from the cyclical recovery and diversify the company’s revenue stream.

The market also loses sight of the entertainment division’s syndicated content, which CBS continues to leverage in an effort to reduce its dependency on ad sales. For example, although the last episode of I Love Lucy aired in 1956, the company continues to receive royalty payments from this franchise. By the same token, the networks’ more recent hits should continue to generate revenue far into the future. All of this content becomes even more valuable as demand for digital access increases.

CBS Corp grew overall ad revenue by 6 percent in 2010, and this momentum should carry over into 2011. Strong results, coupled with a recently announced $1.5 billion share repurchase, should push the stock higher.

Scripps Networks Interactive (NYSE: SNI) boasts a stable of cable TV networks that includes HGTV, Food Network, Travel Channel and DIY Network, all of which feature lifestyle programming.

TV is a big part of Scripps’ business model, but it’s not wedded to the boob tube. Companion websites for all of its networks are the foundation of its growing Internet presence, while the company also provides streaming video content for smart phones.

Although Scripps has benefited from higher affiliate fees as contracts with pay-television providers come up for renewal, significant increases in advertising sales continue to contribute meaningfully to overall revenue growth.

Scripps has become popular with advertisers because its lifestyle programming tends to attract affluent viewers with high disposable incomes. In addition, advertisers can get favorable rates by bundling their ad buys to include both airtime and space on Scripps’ websites.

Scripps’ fourth-quarter results should benefit from strong scatter pricing, which has increased at an average quarterly rate of 15 percent in 2010 and jumped 23 percent in the final quarter of the year.

The company continues to aggressively leverage its content, recently inking a deal to distribute programming through AT&T’s (NYSE: T) high-speed U-verse network, which reaches 2.7 million subscribers. Deals with global satellite and cable TV service providers ensure that Scripps’ content is also available on every continent.

Investors looking for a broader play on these cyclical trends should consider PowerShares Dynamic Media (NYSE: PBS). With assets spread across 30 media-related stocks of all market capitalizations, the exchange-traded fund includes traditional names such as News Corp (NSDQ: NWSA) and Gannett (NYSE: GCI) as well as Google (NSDQ: GOOG) and other online properties. Advertising outfits such as Omnicom (NYSE: OMC) are also in the mix.