Have you ever typed "help for" at a command line? If you write a lot of batch files, read through it and you'll probably save yourself some time. Today I was trying to figure out how to get just the filename out of a path that may or may not contain the fully qualified filename. All I had to do was "%~nx1". Brilliant! Here are a few more nifty variable modifiers from the help docs:

%~I - expands %I removing any surrounding quotes (")
%~fI - expands %I to a fully qualified path name
%~dI - expands %I to a drive letter only
%~pI - expands %I to a path only
%~nI - expands %I to a file name only
%~xI - expands %I to a file extension only
%~sI - expanded path contains short names only
%~aI - expands %I to file attributes of file
%~tI - expands %I to date/time of file
%~zI - expands %I to size of file
%~$PATH:I - searches the directories listed in the PATH environment variable and expands %I to the fully qualified name of the first one found. If the environment variable name is not
defined or the file is not found by the search, then this modifier expands to the empty string

The modifiers can be combined to get compound results:

%~dpI - expands %I to a drive letter and path only
%~nxI - expands %I to a file name and extension only
%~fsI - expands %I to a full path name with short names only
%~dp$PATH:I - searches the directories listed in the PATH environment variable for %I and expands to the drive letter and path of the first one found.
%~ftzaI - expands %I to a DIR like output line