Series One ($8.99 for six episodes)
Series Two: Gdansk - Helsinki - Ipswich - Johannesburg - Kuala Lumpur - Limerick ($1.99/episode)
Christmas Special: Molokai ($1.99)
Series Three: Newcastle - Ottery St Mary - Paris - Qikiptarjuaq - Rotterdam - St. Petersburg ($1.99/episode)
Series Four: Timbuktu - Uskerty - Vaduz - Wokingham - Xinzhou - Yverdon-les-Bains ($1.99/episode)
Benedict Cumberbatch was my personal gateway drug, as he voices one of the pilots, but it's really wonderful for other reasons as well. It's the story of a plucky little airplane charter company and their efforts to stay afloat, which is really great fun in a Wings sort of way, but it's the characters that really make it stand out: a disgraced + maverick pilot who couldn't get a job anywhere else balanced out by Cumberbatch's role, a by-the-book stickler who isn't good enough to get on anywhere else, along with the owner, an older divorcee who is snarky and tough but really is quite sympathetic once you get past that, and her son, Martin who is (there's no other way to put it) an idiot. He's what we medievalists would have called a holy fool, and he's childlike in good and bad ways, but really he's just got this infectious naivety about him. Which is all the more wonderful when you realize the man who voices him is also the creator of the series. The fact that he'd take this role for himself is telling, I think.
The first two series are consistently excellent. They make me laugh when I don't think anything else can. Even the third series (I've only listened through St. Petersburg myself) has a lot of good material, though there are some bits that are a bit repetitive. Even there, though, there are bits that are pure genius. Fo rinstance, by series three the whole bit about Martin (Cumberbatch) struggling for professional recognition has been done and that's at some level the basic plotine of Ottery-St-Mary. But you haven't lived until you've heard yellow car explained, or the theological discussion over otters (I'm not making this up). And really, everything about Rotterdam and the ending of St. Petersburg, and... yeah. Even when it's B+, it's still well worth a listen.
Do check it out if you need a listen.