.inetloc files. Mostly commonly used for HTML links but they can also be used to create SSH logins. They're easy to create too: just type something like

ssh://soandso@whatshername.com

into virtually any app (I use TextEdit), select the text and drag it out to some Finder location. It will create the file automatically. Then just click on the file (or open it with Quicksilver, Alfred, et. al) and it will open a new Terminal window with you ssh'd to the host as that user (normal auth procedures apply).

I don't use them too much anymore because there doesn't seem to be any way to get iTerm2 to be the default app to open such files (on modern MacOS versions the application drop-down in the Finder info window is greyed out) and I don't SSH into as many machines as I once did.

EDIT: turns out you can get iTerm2 to be the default opener for ssh .inetloc files; it's just done inside iTerm itself.

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