Okay, I'll admit, this is going to sound like spam, but I thought it would be of interest (and relatively on-topic) to the group, so that's why I'm posting it. I have no financial interest in this company. That being said...
A friend of mine showed this to me (see? sounds like spam already, doesn't it?): eMachineShop is essentially an easy-to-learn CAD program useful for designing small parts (say, for example, prototype parts) with an eye towards actual manufacture. In addition to merely coming up with the physical dimensions, you also choose the material and what actual shop machines will do the cutting/shaping/etc. The software will also double-check your design to make sure the machine you selected is able to make the cuts you requested. You can then get pricing information for the part based on number of copies, etc. I found it IMMENSELY useful for a component-intensive design of mine...perhaps others will as well. (Oh, and did I mention the very helpful tutorials you can download?)
And for those who aren't internet-savvy, two ways to find it: ye olde google search, or guessing that "www." precedes and ".com" succeeds the subject line.
