New freeware is ready to go.
It is small utility that attaches it-self to context menu of all files. In that way, calculating sum is always near. Do not worry, that option can be turned off. In such case you can use standard user interface to add files and calculate their sums. In case that you need command-line, again, it is there. Supported algorithms include CRC-16, CRC-32, MD-5, RIPEMD-160, SHA-1, SHA-256, SHA-384 and SHA-512.
Summae.exe is main program that is used to select files and configure settings. SummaeExecutor.exe has command-line interface. Sum.exe is command-line interface. It may come in handy in cases where scripting support is needed.
For readers of this blog, I added download of zipped files also. If you prefer to try software without installation, this is way to go.