Are the free toolbars available from several sources handy utilities or a backend pipeline into your computer and your privacy? As they say, it depends on how you look at it.
The Good. I use the Google toolbar. It has several good features that enhance searching and it has the ability to display a page's page rank based on Google's assessment of the site's importance. For bloggers, this is a handy way to keep up with rankings. The Google toolbar also includes a pop-up stopper that works well and can be selectively set to allow popups for sites you choose.
The Ugly. I have to say the Yahoo! Companion qualifies for the Ugly category not because of its looks, which are marginally OK, or even its name, (companion?), but because its search is limited solely to Yahoo! listed sites.
The AltaVista toolbar also qualifies as Ugly at this time, although it is very close to being good. It has all the necessary features, including a pop-up stopper and the ability to translate a site into any of ten languages. However, its only shortcoming at this point is that it lacks a certain amount of accuracy in its info button which is supposed to take you to weather forecasts and so on. Also, its method for ranking sites seems to provide only outdated information. I do have to say that the AltaVista toolbar is worth looking at and may rank as Good for many people.
The Bad. There are several toolbars and utilities that are nothing but spyware that are designed to track your habits and clutter your computer with ads. One of the worst offenders is Xupiter. I won't even post a link to them, but I will post a link to a site that explains how to get rid of Xupiter if you are unfortunate enough to be infected with this parasite. There are many more that are similar, so beware.