Clipboard Help+Spell - Clipboard Help+Spell is a text-based clipboard utility with the following features:
tinySpell - A spell-checker for Windows. Checks text in clipboard and/or on the fly in any Windows program. Small and easy to use. Resides in the taskbar notification area. Free download.
FreeSpell - FreeSpell is a spell checker for any and all Windows applications.
Hunspell - Hunspell is the spell checker of LibreOffice, OpenOffice.
ClipMem 3 - Advanced Clipboard-Manager
GNU Aspell - GNU Aspell, usually called just Aspell, is a free software spell checker designed to replace Ispell.