As an alternative to mucking about with the compiled-in aspell/pspell functions, which only check word by word, one could write a script that calls aspell as a shell exec to check a whole block of text:
http://chxo.com/scripts/spellcheck.php
(there is a view-source option)
Not sure about Linux or Windows, but installing aspell on FreeBSD was trivially easy from the ports collection. No doubt such a script could be easily modified to use ispell instead if you'd rather.