Previous posters have pointed out perlish case/switch hacks so I will not even go there. However if are dependant on the values of multiple variables nested ifs will be more efficient as the value of each var is only tested once..

if ($a==1) {
    if ($b==1) {#do a1b1}
    else {#do a1b2}
}else{
    if ($b==1) {#do a2b1}
    else {#do a2b2}
}
[download]

See, it is a feature not a limitation :-) but you are right it is not as good looking as a case/switch statement.

Cheers,
R.