The Terra Lycos group said on Tuesday that "Nick Berg", "War in Iraq" and "Muntada al-Ansar", an armed Islamist group, were the top three searches made in the week to 15 May.
"War in Iraq" became the most sought topic the previous week after the release of images of the abuse of Iraqi prisoners by US troops, knocking American celebrity Paris Hilton off the top spot.
Hilton and pop star Britney Spears had dominated the web search rankings for months.
But Berg, a 26-year-old US civilian who was abducted in Iraq, has taken over since images of his decapitation were put on a website, run by Muntada al-Ansar, last week.
Terra Lycos said that in the 48 hours following news of the
execution, the most popular search requests included "Nick Berg video", "Nick Berg beheading", "Nick Berg execution", "Nick Berg beheading video" and "Nick Berg decapitation video".
"Nick Berg-related searches are so prevalent that they dwarf all other searches, including the consistent pop-culture leaders"
Internet search group
"Nick Berg-related searches are so prevalent that they dwarf all other searches, including the consistent pop culture leaders.
Top 10 internet searches in the week ending on 15 May, as released by Terra Lycos internet group, are:
1. Nick Berg, 2. War in Iraq, 3. Muntada al-Ansar, 4. Britney Spears, 5. Clay Aiken, 6. Paris Hilton, 7. Al-Qaida, 8. Kazaa, 9. Aljazeera, 10. Survivor.
Quoting an unnamed senior Iraqi source, AFP reported on Tuesday that four men had been arrested in connection with Berg's beheading.
The US military did not confirm the report, however.