is there a simple compression program with gui, that I can use to drop a few files into a window
and have them zipped?

AFAIK, no (but if someone knows it, let us know). But you can create an Ambient menu action to zip/unzip files using MimeTypes.
First of all, you need zip command to put in SYS:C/ so download http://aminet.net/util/arc/zip201x.lha and put zip in the aforementioned directory. I know that MorphOS version exists but I tried to generate a zip file that seems to be ok but if you open it you will find a 0 kbytes directory (though the zip file dimension is correct). In any case here it is: http://aminet.net/util/arc/ZipMOS.lha
Then open Ambient settings/MIME/internal and double click x-morphos-globalaction-file. Click on Add and when windows will appear give a name to this action ("Create zip archive..." f.e.), select "AmigaDOS" as action and write zip -r 'MOSSYS:C/RequestFile' %sf in the text field. Then select "Menu" as Event Type, mark "change current directory in source directory" and "join files", press ok and save settings. When you will select files and/or directories with lasso option, you will have a "creat zip file..." options in the icons menu and once you selected that voice a requester will appear. There you wiil be able to choose the directory in wich the compressed file will be stored and the file name. This could be done even in the "x-morphos-globalaction-directory" settings so to have this option for the directories too.

> http://aminet.net/util/arc/zip201x.lha

As for m68k version, I'd recommend http://www.paulkienitz.net/amiga/zip23xA.zip or http://www.paulkienitz.net/amiga/zcr23xA.zip (with encryption support), which works well on MorphOS and is Zip v2.3 instead of v2.0.1.

> http://aminet.net/util/arc/ZipMOS.lha

As PPC-native version there's also well-working http://aminet.net/package/util/arc/ZipPPC for PowerUP, which is v2.2 like ZipMOS is.

Thanks Andreas! By the way, zip201.x allows encryption but a newer version is welcome. Problem is that I didnt' managed to create a correct archive with any version when I tried to create a mime for directory/ies. Maybe I'm using wrong options.... No problems with zip archive creations with files and unzip process instead.

EDIT:
All is ok. I was working with zip archive creation in RAM and this way doesn't work. My fault.......

[ Edited by Jambalah 26.08.2012 - 14:45 ]

so I can I drop 5-6 files in a folder and compress them using this method?

thanks

I made script for 7zip archiver that can pack several files/drawers in one archive. You can change it for you archiver.

Maybe Peperoni is something for you?

http://aminet.net/package/util/app/Peperoni