Is there any program to provide a consistent interface across multiple archive types?

You can use p7zip. It automatically identifies the archive type and decompress it.

p7zip is the command line version of 7-Zip for Unix/Linux, made by an independent developer.

7z e <file_name>

I found this little snippet a while ago and have been using it since. I just have it in my .bashrc file

extract () {
if [ -f $1 ] ; then
    case $1 in
        *.tar.bz2)  tar xjf $1      ;;
        *.tar.gz)   tar xzf $1      ;;
        *.bz2)      bunzip2 $1      ;;
        *.rar)      rar x $1        ;;
        *.gz)       gunzip $1       ;;
        *.tar)      tar xf $1       ;;
        *.tbz2)     tar xjf $1      ;;
        *.tgz)      tar xzf $1      ;;
        *.zip)      unzip $1        ;;
        *.Z)        uncompress $1   ;;
        *)          echo "'$1' cannot be extracted via extract()" ;;
    esac
else
    echo "'$1' is not a valid file"
fi
}

In Debian/Ubuntu there is the unp package, which is a Perl script that acts as a frontend for many archiving utilities.