With reep.io you can transfer files directly to another browser. Just point to a file you want to share. Your peer will then be able to download this file directly from you. No data is stored on a server in-between.
HashTab provides OS extensions to calculate file hashes and supports many hash algorithms such as MD5, SHA1, SHA2, RipeMD, HAVAL and Whirlpool. As Windows desktop software HashTab runs as a Windows shell extension and on the Mac it is implemented as a Finder plugin. HashTab provides an easy way to verify file integrity and authenticity.
lsof is the sysadmin/security über-tool. I use it most for getting network connection related information from a system, but that’s just the beginning for this powerful and too-little-known application. The tool is aptly called lsof because it “lists openfiles“. And remember, in UNIX just about everything (including a network socket) is a file.