It has been quite a while since the previous summary. So let us not waste any more time!
The yearly meetings for Tclers have already been given a page of their own:
Documenting it all
But online help is one thing, a series of Articles describing not only the "how-to" but also the "what" and "when" of various language features is most definitely a welcome addition.
(... or a few quotations by anyone Who says Tcl rules..., as clearly not everyone is convinced, as a recent post on comp.lang.tcl shows.)
To make things simple
Tip 556: Add oo like widgets to Tk proposes to, well, add oo like widgets.
A programming problem can often be solved in Tcl in very different ways, an example is that of Splitting a string on arbitrary substrings.
Beyond the obvious
We are not easily limited to the ordinary computing devices, as A Tcl extension for FPGA compiled C function direct interaction shows.
Or try Undroidwish on the Raspberry Pi 3: perhaps not for the weak of heart, but persist!