Is there one?
I've just recently made the transition from TS2 to TS3, and I always used the Body Shop to create my sims while playing TS2. It's easier to see all the details and take your time with the sliders. I can't seem to find anything like it for TS3.
Is in-game CAS the only way there is? How do you guys make sure your sims look just right? What mods should I look out for when I want to make awesome sims?
Well, mods like Awesome Mod (from More Awesome Than You) or Master Controller (from Nrass Industries) are both useful when it comes to making sims, since one of the features is a Slider Range increaser, where you can increase the range of the base game's Sliders, allowing you to achieve a wider range of options then normally allowed. They also increase the amount of Sliders that will show in CAS, since there is a set amount of spaces that will show up, which allows you to download CC sliders and actually get them to show up for use. Just be aware that both of these are big mods, do a lot more than add slider hacks, and need to be updated with each patch. The last few EP's actually included several new sliders that were previously only available as CC (pointed ears, for example). Then it's just a matter of seeing what you want to do that the game doesn't offer, and downloading the appropriate slider for it (things like Brow Thickness or Cleft Chins). There are several sliders on this site, and several more all over the internet. If it's something that can be adjusted, odds are pretty good that there is a slider for it somewhere.
I don't think there is a bodyshop for Sims 3. They did release a Stand Alone version of CAS, but you had to pay for it, it didn't accept CC, and was a big steaming pile of plops.