Americans trying to beat the April 16 deadline to file federal income taxes are converging on the Internal Revenue Service's Web site, IRS.gov, to electronically file their returns, according to traffic-measuring site Nielsen/NetRatings. For the week ending April 8, traffic soared 61 percent at the site to peak at more than 1 million unique visitors. IRS.gov saw 681,000 visitors the previous week, Nielsen said. Last year, a total of 32 million Americans used the Web to file their taxes, the IRS said.