It can be dangerous to download from person to person sites because you can get viruses that will damage the performance of your mobile device. It is not recommended that you get free downloaded software unless its from a trusted site.
Yes, according to the Blackberry company, which can be found on the world wide web, there are free mobile software that you can download depending on the type of Blackberry you have.
Many sources of free software exist. Be careful however not to trust various 'underground' sites! Have a firewall and at least one antivirus installed at all times! Some ways of finding such software...
"The LogMeln software download in free from the Logmeln website. They do require you to register, but they offer a number of other valuable downloads to their members."