I see that WinZip (www.winzip.com) has a new beta test release. It might be "freeware" at least for awhile. I have successfully used the command line option for WinZip in some batch files before. (I believe the current version can be downloaded for free, but has "nag-ware" built in until you buy a license -- about $US 30.00 I think?)
I did a google on "freeware+unzip" and got several interesting hits, but I can't claim any experience with them.