Website: http://www.ofimega.es/oficalc/ (Google translation: http://translate.google.com/translate?js=n&prev=_t&ie=UTF-8&tl=en&u=http%3A%2F%2Fwww.ofimega.es%2Foficalc%2F)


Pros: Tons (tons!) of functions. Cons: The (for my taste) cluttered interface.

ANIGIF>

Download: http://www.ofimega.es/programes/Oficalc.zip

Instructions:

Uniextract the installer. The needed files are in the {app} folder. Launch Oficalc.exe.
Default interface is in Spanish, to change to English select Configurar > Idioma > Inglés - English. Other languages are available.
Note that the english translation is not complete, but it seems to me it's not difficult to understand the functions.

Settings are saved in the application folder. Due to previous installations, I had to manually look for traces and found nothing.
Aparently stealth, then.

License: Freeware

I thought lautrepay had found a pearl!
So many useful functions.The Home Site provided a reasonable overview even if the translation was poor.
I was even prepared to overlook the cluttered interface (yes lautrepay's right about that).
But the truth is this is close to unusable for me. First it's very flaky. It regularly stops working.
Things like stack overflow and out of range indices (try Optics in the Scientific section).
Even when it does work there are a lot of sections still in Spanish.
I even tried installing it using Setup. Curiously that was worse.
A great pity. Because this has great potential.
I suppose the odd thing is that the program has had many updates and some of the bugs I found should really have been ironed out. I even located an old version (9.5) and tried that - just as bad.

I'll sit back now and wait for further comments to roll in (eg works flawlessy; cannot do without it etc)