I've acquired other companies, but the sale of Mollom to Acquia, was the first time I sold a company of my own. Being the seller felt quite different. It's a interesting mixture of satisfaction tinged with loss. During the negotiation phase you feel joy and excitement. Then you feel frustration as you go through the due diligence process. It's a lot of work. Eventually, the day you hand over the keys you feel like you sold your baby. At the same time, you feel a sense of achievement.
Selling Mollom was a life-changing moment. Not because it was a big financial transaction (it wasn't), but because it proves that I was able to bootstrap and grow a company, steer it to profitability, and successfully exit. It was a great experience, because I know that at some point, I'll have the desire to do that again.