Hey Donald, it can be feast or famine, a strange business for sure, at times.
A good opportunity to read some books (tree work or other), practice your knots, develop your skills, read Treebuzz (spoken like true Buzzaholic). Make yourself a more marketable employee for your current job, or to work in with another crew part or full time.
You can offer to help with marketing if the boss is too busy taking care of maintenance, etc. Posting flyers in appropriate areas, such as local grocery stores, coffee shops, etc. A little work means a little money. Initiative and self-motivation are traits that employers love to see, whether he takes you up on the idea or not, your employer will see the willingness.
You can offer to help with any maintenance, truck washing, etc.
Keep your company's business cards in your wallet, and give them away to family and friends that own their own homes, and people that you talk to that seems like possible jobs. Hopefully, you might even get a small finder's fee if you drum up some good work. I always offer one if my employees bring some work in. Just try to screen who you give them to, so as not to waste your bosses time/ money if people want something for nothing.