Techshare: JDownloader and Hamachi.

Oftentimes large downloads (MMORPGs, I'm squinting at you) are split into separate parts for easier user-end consumption. Normally, this is okay- but when a file has, say, 45 parts of equal size hosted on a provider that makes you wait before starting a download (Megaupload and Rapidshare, for instance) and doesn't permit concurrent downloads, a healthy (free and legal) option is to use a neat application called JDownloader. It's a Java-based batch downloader that even supports all sorts of useful functionality, like grabbing links from your clipboard, parsing pages for more links, and more!

One of the handiest applications that I've discovered.

Also nice for gaming sorts of things is Hamachi. They offer a few different flavors, but the type I endorse is their noncommercial free-to-use version. Hamachi creates a virtual Ethernet adapter that allows virtual LANs to be created on-the-fly, permitting solutions for users behind firewalls or other internet interfaces to network in a fashion that doesn't require complex things like portforwarding.

What tech would you like to share?