The other day I turned down an opportunity to take part in a focus group. My father owns a market research firm, which is always an immediate red flag in pre-screening, so I just preempted the inevitable. But it KILLED me. I could have earned $125. Just for opinions!

The offer got me thinking about creative ways to bring in cash when the paychecks aren’t rolling in. I talked to friends and experts and searched the web. Here’s what I found:

Most Lucrative: Dog Walking

Cait, a former colleague who lives and works in Chicago, walks three to five dogs during her lunch break—every weekday! She spends five hours per week doing it and makes as much as $225. That’s $45 an hour! If you can swing a regular break, it’s good exercise too. Cait recommends putting up flyers to get the word out in your neighborhood. It doesn’t hurt to have a reference or two; you can start by walking a friend’s dog.

Oddest: Selling Your Hair

Catey Hill, author of SHOO, Jimmy Choo! The Modern Girl’s Guide to Spending Less and Saving More, says you can earn a few hundred dollars selling your hair. Buyers are usually wig- and doll- makers, and thick, “virgin” locks can fetch top dollar (bottle blondes like me need not apply). Interested? Start growing yours now. Most sellers offer 10 to 12 inches (after cutting). Check out Hairwork.com for more information.

Lots of Options: Secret Shopping

Catey also suggests signing up for “secret” shopping, which is basically pretending to be a shopper to check up on customer service at a business. I tried it once two years ago myself. I signed up at TrendSource.com and I was emailed a lot of listings each day. I never wound up taking an assignment because most paid poorly (around $10) and were in out-of-the-way locations (without a car), but it could be a good deal. One job advertised paid $50 to visit an automobile showroom and test-drive a car.

If you do it, Catey says, make sure you’re signing up with a member of the Mystery Shopping Providers Association. You can learn more at www.mysteryshop.org.

Most Social: Guest Bartending

Moneymaking doesn’t have to interfere with your social life. A friend who guest bartended at a dive bar on the Lower East Side in Manhattan recently brought home $150 in tips one Thursday night. And she got to hang out with her friends.

Interested to try it where you live? A quick Google search yields pages of results in many local cities.

Most Career-Oriented: Freelancing

Freelancing is much less intimidating than it may seem. If you have a skill you’ve honed (perhaps with on-the-job experience) as well as a couple good references and the confidence to sell yourself, you’re in good shape already. Your network can get you to your first few gigs and if you like it, you may just end up self-employed.

This article from Entrepreneur magazine outlines more basics and even includes a list of “types” of freelancers: http://www.entrepreneur.com/startingabusiness/businessideas/article79088.html

Or try The Freelancers Union (http://www.freelancersunion.org/), which is a great resource for workers in all fields.

Here are some other ideas:

Babysit

Deliver phone books

Teach English as a second language

Sell stuff on eBay

Clean houses

Sell your eggs or sperm

Participate in medical testing

Get cash for old ink cartridges

Unload old CDs/DVDs

Sell your old mobile phone(s)