How about a konqueror service menu that could accomplish this? I made a simple one like so.

[Desktop Entry]
ServiceTypes=audio/x-wav
Actions=convertToOgg

[Desktop Action convertToOgg]
Name=Convert to ogg
Exec=oggenc %U

Theres a very good Service menu how-to here http://developer.kde.org/documentation/tutorials/dot/servicemenus.html

Created attachment 3842 [details]
service menu example

Sample .desktop service menu file.

This is what I do, maybe someone can improve it, lame and oggenc have to be installed:

$ cat kwavenc.desktop

[Desktop Entry]
ServiceTypes=audio/x-wav
Actions=b64;b128;b192;lq;mq;hq;custom

[Desktop Action b64]
Name=make a 64kBit MP3
Name[de]=ein 64kBit MP3 erzeugen
Icon=sound
Exec=xterm -e "(echo m;echo 64;echo n)|wavenc %f"

[Desktop Action b128]
Name=make a 128kBit MP3
Name[de]=ein 128kBit MP3 erzeugen
Icon=sound
Exec=xterm -e "(echo m;echo 128;echo n)|wavenc %f"

[Desktop Action b192]
Name=make a 192kBit MP3
Name[de]=ein 192kBit MP3 erzeugen
Icon=sound
Exec=xterm -e "(echo m;echo 192;echo n)|wavenc %f"

[Desktop Action custom]
Name=make a customized MP3 or OGG
Name[de]=ein MP3 oder OGG erzeugen, mehr Optionen
Icon=sound
Exec=xterm -e "wavenc %f"

[Desktop Action lq]
Name=make a low quality OGG
Name[de]=ein sehr kleines OGG erzeugen
Icon=sound
Exec=xterm -e "(echo o;echo 0;echo n)|wavenc %f"

[Desktop Action mq]
Name=make a normal OGG
Name[de]=ein normales OGG erzeugen
Icon=sound
Exec=xterm -e "(echo o;echo 4;echo n)|wavenc %f"

[Desktop Action hq]
Name=make a high quality OGG
Name[de]=ein hochqualitatives OGG erzeugen
Icon=sound
Exec=xterm -e "(echo o;echo 7;echo n)|wavenc %f"


$ cat wavenc

#!/bin/bash

export IFS="
"

test -z "$1" && echo -e "\nusage: wavenc file.wav\n" && exit

function makemp3()
{
        temp=`echo $1|sed 's/.wav$/.mp3/g'`
        mp3name="`echo ${temp}|sed 's/.WAV$/.mp3/g'`"

        echo -e "\nbitrate? [32,40,48,56,64,80,96,112,128,160,192,224,256,320]"
        read -e bitrate

        echo
        echo "Stereo -> Mono? [y/N]"
        read -e mono
        if [ "${mono}" = "j" ] || [ "${mono}" = "y" ]
        then ifmono="-a"
        fi

        echo

        nice -10 lame -b ${bitrate} -h ${ifmono} "$1" "${mp3name}"
}


function makeogg()
{
        temp=`echo $1|sed 's/.wav$/.ogg/g'`
        oggname="`echo ${temp}|sed 's/.WAV$/.ogg/g'`"

        echo -e "\nquality (higher is better)? [-1..10]"
        read -e quality

        echo
        echo "Stereo -> Mono? [y/N]"
        read -e mono
        if [ "${mono}" = "j" ]
        then ifmono="--downmix"
        fi

        echo

        nice -10 oggenc -q ${quality} ${ifmono} "$1" -o "${oggname}"
}


echo -e "\nMP3 or OGG? [m/o]"
read -e enctype


if [ "$enctype" = "o" ]
then makeogg $1
exit
fi

Maybe I try improve the service menu and put it on kde-apps.org