When it comes to downloading programs, you always want to go to the source, however, this isn't always possible if the application in question doesn't have its own website and instead is distributed via SourceForge or CNET. In this case, you'll often have to deal with an adware-wrapped installer and while vigilance will make sure you get the download you want, we all slip up. Fortunately, a simple extension can remove human error from the equation.
The script, called "Fake-Download Bypasser", which can be used with Firefox and Chrome, will alter links on pages so they point to the actual file download, rather than the wrapped one. At the moment, it works with CNET and SourceForge, as well as AfterDawn and CoolROM, if you happen to frequent those sites.
As Martin Brinkmann at gHacks explains, you'll need Greasemonkey to use the script on Firefox, while a manual extension install is required for Chrome. It also just redirects you to the correct download, rather than changing the appearance of the site / button, so it's definitely more for the absent-minded file grabber.
Again, try and track down the original program author if you can -- not only are you assured of clean files, you'll know where to go for the latest versions and support.