Definite competition for Google's toolbar, the Yahoo! Toolbar for Internet Explorer and the newly released (in beta) Yahoo! Toolbar for Firefox offer solid search capabilities, a pop-up ad blocker, an anti-spyware scanner (in the IE release), and lots of customization options.
At 3MB (with the spyware option — under 400KB without it) the Yahoo! Toolbar is a larger download than the other major browser toolbars, but it quickly and easily installs itself. The toolbar offers a wealth of customization features to reorder buttons and view icons or text, and recent versions make it possible to alter the size of the search text box.
Using the Yahoo! Toolbar, you can search the entire Web or limit searches to specific sites that you visit, as well as search specifically through Yellow Pages or for news, stock quotes, products, maps, movie showtimes (based on zipcode), and more. As with the other toolbars, you simply select your option from a convenient drop-down menu.
The toolbar also offers single-button access to Yahoo! e-mail with options to compose e-mail and more. A highlighter indicates where search results appear on a page. Like the Google toolbar, the Yahoo! Toolbar features a competent pop-up ad blocker that lets you look at ads that it has already blocked and also allows you to create a whitelist of ads to display.
The Anti-Spy feature clearly sets the Yahoo! Toolbar apart from and ahead of the others. This feature scans your computer for questionable applications and reports a list of suspicious files. And another plus, there's a handy bookmark feature that maintains the bookmarks that you store in Internet Explorer.
On the downside, Yahoo! Toolbar does lack the handy automatic form fill-in features found in Google Toolbar and MSN Toolbar.
Despite this lone shortcoming, Yahoo's Toolbar is, for now at least, the strongest of the three major toolbar offerings and the only one to currently offer a version for Mozilla Firefox. If you already rely on Yahoo or if you're using Mozilla Firefox, it is clearly the toolbar of choice.