Sarcasm is a Z80 assembler written in Perl. Perhaps its best feature is that it is totally awesome. Second to that would be... ...yes, definately the multiple instructions on a line seperated by semicolons. If that idea turns you off, you'd best go elsewhere because there's a lot more where that came from. Can you say "pays more attention to whitespace than commas" without having a seizure? It truly is an awesome assembler, even if it seems that nineteen out of twenty people are completely uninterested after reading this page.
The current version is 2008-05-01 but you may wish to download any of the available releases. Rest assured the old ones kind of suck. In fact, you may think of that of the latest release too. Who knows. The documentation could be better.