In the last few weeks, I've advised a couple of companies as they have worked to source candidates for critical senior level positions. In doing so, I was reminded of a very important resume truth – at least based on the way the "other side of the table" sees something that you (the candidate) likely view entirely differently. In most situations, don't put a side business on your resume.
In this, the Career Development side of my work, I partner with many outstanding job candidates who have been out of work for several months. Some have put the time to good use by consulting / contracting in order to keep their skills in top form. Also, many feel a side business bolsters their resume because it shows a continuous work history, no gap on the resume, entrepreneurial savvy, etc.
With stacks of resumes representing qualified candidates, companies get to the point where – with everyone looking so good – they have to start uncovering reasons to eliminate you from the running. In my experience, many HR professionals and hiring managers will view you as a flight risk if they see a recent personal business (even temporary) on your resume. As one of my clients said last week:
This guys looks like he'd be a great hire, but it also looks like he's been building up his side business since his last position. He's not going to dismiss all of that momentum. I bet if we were to move forward with him and his business were to really take off, he'd quit.
For every employer or two who would appreciate seeing such work on your resume, eight or nine will view you as a risky hire. Be very selective regarding when you choose to share this information. Similarly, if you do, say, side consulting during your off hours, don't highlight that either. The competition is stiff right now, and you don't need to include any distractions that might be perceived as spreading you too thin.
Keep in mind, though, that there are ways to present this kind of experience without giving the impression that you are a less than ideal hire.