Drawing those eyeballs (and making them stay)

As Fred Thompson officially enters the presidential primary, he already has a leg up in some polls. It turns out, he also has an edge among his Republican competitors when it comes to web traffic.

According to Nielsen//NetRatings, Thompson led the Republican field in July in unique visitors to his website, with 381,000. Rudy Giuliani came next, with 124,000, followed by Mitt Romney with 116,000, Ron Paul with 113,000, and John McCain with 104,000.

But Democrats led the field overall in terms of drawing people online. Barack Obama's website drew 717,000 unique visitors, followed by Hillary Clinton's with 437,000 and John Edwards' with 348,000.

Just as intriguing are Nielsen's calculations for the average time visitors spent in July on each campaign site. Among the Democrats, Hillary Clinton's visitors spent the most time on average (eight minutes and 17 seconds), followed by Obama (seven minutes and 53 seconds) and Edwards (three minutes and 43 seconds).

Among Republicans, Giuliani fared best: Visitors to his website spent an average of seven minutes and 33 seconds. Paul came next (six minutes and 52 seconds), followed by McCain (one minute and 47 seconds) and Thompson' (one minute and 35 seconds). As for Mitt Romney's site? The average visitor stayed for 49 seconds.