I was talking to Alexia, and mentioned Obsidian Portal while discussing d20 games, and I realized I should have mentioned this here a long time ago. There are two programs I use for playing d20 games with other people over the internet, or even sometimes use them in person. They're pretty handy. The first is Hero Lab. Really, really handy for leveling your character and making sure everything is legit. Also, I use it to keep track of my weight, among other hard to track things you usually forget about in the heat of the moment. It's a free download, but buying the books to access the material in them cost money. Second is the aforementioned Obsidian Portal website. Lacrifish actually introduced it to me. I was building my own campaign using that for my first ever experience DMing a home-brewed campaign. I found it fun and easy to use at the time. It's gone through some major overhauls since I used it last year, but it looks nice. It's free, but if you pay for a yearly subscription fee (or monthly if you expect to be using it intermittently), you get a bunch of other handy futures. Though if it's worth the $39.99 yearly fee (not too bad even to my cheap ass), that's up to you. Only one person needs to have it in the party, usually the DM. Though people can be promoted to DM, and then they can promote someone else to co-DM or DM. If anyone has any resources they think would be useful on this topic, feel free to share it with a bit of an explanation of what it is and does!
There's also roll20 for an actual table top surface to play on, once you have your campaign on a roll. Magnus has actually been using it for his out of vehicle combat in MegaMek, and it's a pretty decent web platform.
I have a few keys fir Fantasy Grounds II. Roll20 is great for free. FGII is amazing for automation and streamlining
I use Hero Lab a ton! I create NPCs for my modules, PCs for my games, etc. Roll20 has been the main program I have used for gaming in the Borg (Pathfinder, MechWarrior RPG, Shadowrun, and now Rogue Trader).
Yeah, creating NPCs with Hero Lab is a huge help. That's what I was doing for my campaign I was DMing. It saved me a ton of effort, and I could pull of things on the fly if I needed to, and even tweak them for special surprises really quickly and easily.