How to avoid drive-by downloads of the ask.com toolbar with each update of the Java runtime (JRE)
[15-Aug-2012] Oracle still continues the questionable practice of bundling the ask.com toolbar with each security update of the JRE, even going so far as requiring the user to opt-out of the installation of the potentially unwanted additional piece of software.
To avoid this, do not download the "standard" ("Online") version of the JRE, but instead go here and install the "Windows x86 Offline" installer - once you installed this version for the first time, future downloads will also exclude the ask.com toolbar. This is probably a particularly good idea if you are installing JRE for someone else who may not want to be nagged each time there is a new security patch.
Update [17-Oct-2014]: While the above "trick" no longer seems to work, Oracle have now added an option to the very bottom of their Java control panel's "Advanced" tab named "Suppress sponsor offerings when installing or updating Java". Check this, and you should be done - very useful if you are setting up a PC for someone else. See How-To Geek for more details.
In the German version, the option is called "Sponsorenangebote während der Installation oder Aktualisierung von Java unterdrücken".