Hi,
1) sometimes styles requires to use small vertical indentation  between paragraphs
and naturally  we choose to  use \parskip and it leads to some painful programming dealing with spaces
For example after float if there will be paragraph  the space will be \textfloatsep + \parskip.
The problem is that there is no control on this and I want to ask consider the possibility to add
some  tokens list like \everyparskip{} which  would be inserted before \parskip where could be possible
to check \lastskip:

FOR EXAMPLE:
\parskip=5pt
\everypar{\showthe\lastskip}
a
\vskip20pt

\showthe\lastskip
b
\showlists
\bye

STDOUT:
> 0.0pt.                              
<everypar> \showthe \lastskip         
                                      
<to be read again>                    
a                                     
l.3 a                                 
                                      
?                                     
> 20.0pt.                             
l.6 \showthe\lastskip                 
                                      
?                                     
> 0.0pt.                              
<everypar> \showthe \lastskip         
                                      
<to be read again>                    
b                                     
l.7 b                                 

POSSIBLE PLACE OF \everyparskip:
.\tenrm a
.\penalty 10000
.\glue(\parfillskip) 0.0 plus 1.0fil
.\glue(\rightskip) 0.0
\glue 20.0
----------- HERE
\glue(\parskip) 5.0
\glue(\baselineskip) 5.05556
\hbox(6.94444+0.0)x469.75499, glue set 444.1994fil, direction TLT
.\localpar
..\localinterlinepenalty=0
..\localbrokenpenalty=0
..\localleftbox=null
..\localrightbox=null
.\hbox(0.0+0.0)x20.0, direction TLT
.\tenrm b


Or \everyparskip{} could be always in the format like \everyparskip{\vskip\parskip} and one could deal with it.

Thanks, Linas