Tools of the trade
Let's take a look at the stuff you might need for your wonderful conceptual artworks. Below there is a list of the tools I use, most of which are currently industry standards.
Pencils, pens and markers
The most common traditional media tools, easily obtainable, always reliable, the most difficult to master. However, if you can't create a great design with nothing but a pen and rely mostly on software, you're just a techie, not really an artist. Some people are awesome with digital art, know every hotkey, know how to seamlessly combine 2D with 3D, etc. but if they don't have access to their magical tools, say, they're computer is down, they're busted. Don't be one of them.
Digital art applications make certain things very easy. Powerful custom brushes, 3D cameras, amazing visual effects - all this is fine but will not replace a quick, accurate sketch. Of course, you can use Photoshop or Painter as your sketchbook but ordinary pencil and paper are just faster and more intuitive.
Pencils vary from H6> to B6>. For sketching, HB or B are just fine. Personally, I almost never use anything elese than a simple mechanical pencil that allows me to be quick and detailed but you can use whatever works for you. You can also use pens, e.g. 0.3 or 0.5mm, either by themselves or to track your initial pencil sketch. Markers can be used for blocking shadows or to emphasize strong silouette. Markers from Copic company are popular among many artists and my personal choice as well, but any kind will do. Don't switch to markers unless you know what you're doing and how to use them properly. If you don't, you can quickly ruin a good sketch and, of course, you can't erase the marker. If you're afraid to mess things up but want to add some values in a marker "style", you can always do it later in Photoshop or Painter. Or first scan your sketch to have a digital back-up (just in case) and then use markers.
Industry standard and the most popular 2D software out there. The best remedy for almost anything, from retouching holiday photographs taken by your granny, to creating complex digital paintings. You can get a free version (called Photoshop Elements) when buying some hardware, like a scanner. If you can't afford the latest version, don't worry - for concept design and even for detailed matte paintings, you don't need more than just a few standard tools that can be found in almost all versions of PS (from PS7 upwards).
Another popular 2D application, designed to imitate natural brushes in a digital world. Very comfortable for quick digital concepts, have some great brushes and you can easily rotate the canvas just like a real page. It's also perfect for those with more artistic approach (although the latest installment of Photoshop offers similar "panterly" features). Painter is often used together with PS, as both applications can exchange the .psd files (together with layers). It's not absolutely necessary in your arsenal but it's definitely good to have it. Alternative include e.g. Gimp, ArtRage or Sai.
There are many popular packages out there, like Maya, 3ds Max, XSI, Cinema 4D, modo or even freeware, but very powerful, Blender. Nowadays, it doesn't matter anymore, especially for concept art, as apart from some high-end proprietary features, they are all pretty much comparable. For artists, it's really just a matter pf personal choice. Whatever your choice may be, make sure you learn the software well (for concepts - mostly modeling and quick rendering) and keep trying different techiques. Most of the 3D packages are very complex and it's hard to become an expert in any of them but you have to be able to model anything you might need for the sake of your designs. Make sure you know how to use basic materials, lights and in-built renderers. Even if you want to focus only on design, such knowledge may be very useful and will allow you to realistically present your ideas, especially those "mechanical" or related to architecture, like interiors.
As an additional 3D software I recommend Google SketchUp. It can be downloaded for free and it's a great tool for quick 3D design or layout, very helpful when dealing with architectural elements and composition. Spend a few minutes in SketchUp, make a screenshot, open it in Photoshop and paint over it.
Software that soon after its release changed the whole industry. Ability to sculpt in millions of polygons allowed artists to put enormous amount of details into 3D models and make them more realistic than ever before. ZBrush gives lots of possibilities to modelers as well as to concept artists dealing with something organic - never before posing ans creating a creature was so easy. Definitely a good investment. The latest installments also offer tools for hard-surface modeling/sculpting.
Just like Nuke, Fusion or Shake, AE is a compositing software. What does it mean? It allows you to combine and modify almost any kind of 2D artwork, 3D render or video clip. This kind of tool is often used together with 3D package as it allows to import render passes and combine them as you see fit. But how can it be useful to concept artist? Every compositing application can use tons of presets and f/x effects you can apply to your art and preview everything in real-time. It may be really useful, especially for action-related, more "cinematic" artworks.
So, there you go, my few cents. Feel free to post any comments or questions. Till mext time.