Well, don´t listen to Moc on line 2, he IS a jetbike god :-) Or at least one of the most competent people around here.
My style is a little different though in some part, I´ll get to that later though (I´m from Ulthwé, so some difference is only logical :-)).
The biggest importance is, whether you want to be jetbike heavy, or if you want them just as some sort of addition. They tend to get costly rather quickly, and if you have half army slow, half in jetbikes, it won´t be very good I think. They don´t have the stopping power good enough I think. But if whole army is very fast, they are lethal, as they don´t have to stop anything...As addition to different theme army I´d take them as vehicle hunters - either just 3 with shuricannon, or I´d add warlock (it makes the squad much more powerful, but much more costly too).
I use small squads of 3 bikes+warlock (singing spear+destructor). I prefer to have smaller squads - sacrifices hurt less, easier to hide, can be a little confusing for my opponent etc.
For melee, I would never use them - I have shining spears for that. But seriously, bikes ordinary guardsmen, which cost triple the points...
My tactics is based on the fact, that I can quickly move them where I want - so I wait, shoot with cannons and hide, kill some models with mind war, and when I see my opponent made a mistake (he always does), I doom some squad (with two seers, I can doom two squads), strike at them with several units of jetbikes combined. I mean, if you have only two small squads I mentioned, it´s 4 TL shuricats, 6 SC shots and two destructors - when the unit is doomed, it´s pretty good.
I weaken a squad this way and then charge with shining spears (I have a stat table in my head, so I want the unit "prepared" for such number of models, so spears won´t kill them all - they´ll stay hidden in the close combat, and they´ll jump back (ready to charge in my turn).
This way, I hurt my opponent - sometimes I can get to his vehicles, sometimes I just kill mostly infantry...but it works.
It´s tough, as I have to care much about both of us - I have to wait for every little mistake of my opponent, while I have to take care so I myself don´t do a mistake :-) On the other hand, it´s rather rewarding style of playing + the army looks so good.
So, to sum it up, jetbikes are potentially powerful, but I think they should be really a minor addition, or main theme of an army, to be fully effective. Their speed and manouvrability is great, but it´s paid for...