There are some great programs that can be of use to ukulele players. Here are some of the ones I have tried and recommend (plus some ways to use them):
Audacity – Free open-source recording program. It’s simple, but has a decent number of effects to select from.
Powertab – Free tablature editor. Add articulations, note durations, the whole nine yards… The only drawback is that you can’t tab in “just tab format” – the music staff is always there.
GarageBand – The be-all-end-all basic recording program for Mac. Endless learning opportunities as you record yourself to play with or track a song.
TuxGuitar – Another free tab editor. Similar to Guitar Pro, you can use it to open many types of tab files (including Guitar Pro and Powertab)
Transcribe – A high-end “slow-downer” for figuring songs out. There is a free trial period, but after that you have to purchase the program. I’m tight, so I use the Audacity work-around, but Transcribe is easier to use by far.