LiveWire is a neat program that is actually used to design and simulate circuits. This may be a little too technical for people who don't have a lot of experience in electronics and might not know the basics of how circuits work, but for anyone who has a real interest in the subject, or who deals in circuitry on a professional level, LiveWire can be a great learning tool as well as a great way to lay out your ideas before putting them into action.
The software is available in both educational and professional packages, so no matter what end of the spectrum you happen to find yourself on, you'll be able to find a LiveWire package to fit your needs. In any event, the software stores its projects as LVW - Livewire Document files, which means that you'll be able to take your projects from the educational software and keep building on them when you move on to the professional version of the software. This will ensure that your education only serves as a platform, a floor for your experience in circuit design, and not a ceiling.
Circuit design can be a very fun and interesting field, and LiveWire can make it a little more accessible.