You really need to read through this forum. There is a lot of stuff here.
To save you the most of the effort the two big programs are PCGen and HeroLab. These are for your laptop. There really isn't much right now for iOS. HeroLab may eventually come to iPad after they get it out for Mac. However that's a ways out.
Personally I still use spreadsheet programs for most of my characters.
I've been looking around lately when I am in my DnD group, and I notice one or two people using applications on their iphone / laptop in order to make / keep track of their characters. Rather than buying paper when I need a character, I was hoping I could find a character builder application for the laptop for Pathfinder, just to let me keep track of my characters attributes, skills, spells, weapons, ect... If anyone knows of such an application / service, please let me know. I'm positive something is on the paizo shopping pages, I just cant find it.
If you play D&D, there are a lot of different apps for iDevices. For 4e D&D players, 'i4e' is pretty much the standard. For 4e DMs, the compendium app is pretty cool, but you need a DDI subscription. Drums of War is also well-made, but I don't use it too often.
If you prefer D&D 3.5, there's RPG Scribe and some other apps, but they didn't really convince me. You most likely won't find any software that supports all the options in 3.5 because of legal problems. So in the end, I used VoodooPad (a personal wiki) on my Macfor my character and on the phone I displayed the char with VP Reader. The good thing, you can quickly find the text for any splatbook feat or spell or whatever during play, but you'll have to copy-paste or enter it into the Wiki-App first.
I'm afraid there isn't really anything for Pathfinder yet, apart from some overpriced, almost-scam spell book apps.
From what I hear from HeroLab, their Mac version is just around the corner. They've worked out the major kink that was keeping it from being released.
I also understand that the iPad version won't be far behind the Mac version.
Of course, I could be completely wrong on all of this.
Also: I use HeroLab and love it.