recode is a command line tool to recode textfiles between different charactersets and usages. I need it to convert plain text into HTML for example. Since there is no MacOS binary available, you have to compile it on your own which means you need the MacOS developer tools to be installed.
Then all you need to do is this:

tar xfv ~/Downloads/recode-3.6.tar
cd recode-3.6
cp /usr/share/automake-1.10/config* .
./configure --disable-nls --mandir=/usr/local/share/man --infodir=/usr/local/share/info/
make
sudo make install

Then you can use recode like this (works on file too of course):

$> echo "<test>" | recode latin1..html
&lt;test&gt;

I use that very often from inside the vim editor