Tclkit
tclkit and tclkitsh are single-file distributions of Tcl (based on libtcl) that can be launched without prior installation; they store all auxiliary files in an internal filesystem-in-a-database. The main difference between tclkit and tclkitsh is on Windows, where the former is built as a graphical application (so not using real stdio) and the latter as a console application (forcing the opening of a console window if run from Explorer); these differences are a feature of the Windows platform.
Tools are available for simply building user applications into single file distributions based on tclkit, through concatenating a further filesystem-database file. Since this technique is orthogonal (and largely transparent) to the application, it has become a very popular technique for distributing applications implemented in Tcl.