yeah it's either power tab or guitar pro... both are good, they both do the same thing.
I'm afraid that if you wanna learn ukulele you'll have to look harder to find tabs... but they are out there, I have a friends that plays the uke, I will ask him where he gets his tabs.
Other than that, my advice would be, learn the chords, and then look at chord sheets, it's a lot more versatile as the chords remain the same for all instruments, that's what I do, and it hasn't steered me wong so far