Yep, as others have mentioned: Amazon, Ebay, and Craigslist, and in no particular order.
I do tend to lean more towards Amazon these days just because it's generally easier especially for the items you can ship via Priority or First-Class. Basically, smaller/lighter-weight and high-value items are best sold on Amazon because Amazon is somewhat stingy with the "shipping credit" they give you - not sure why they've structured it this way but anything you can fit into a flat-rate Priority padded envelope or small/med box is the way to go. Or if it's under 13oz, even less you have to spend on shipping with USPS first-class. I haven't had any problems doing it this way. They do offer Fedex and UPS which is preferable when shipping larger or bulkier items that require bigger boxes. The great thing about Amazon is how super-easy it is to list items. There are some exceptions of course where you may not be allowed to sell certain things (this is generally rare though)
I haven't sold a whole lot on Ebay (definitely not as much as I used to) probably because it's just more of a hassle create a listing and also they keep jacking up their fees. Between Ebay and Amazon, I find the fees more or less come out to be similar (perhaps with Amazon charging slightly less). But Ebay is great as you have the ability to set the shipping cost (keep in mind that Ebay started charging a fee on that too though - I think 10% of the shipping fee that is set).
As far as Craigslist, I've noticed I haven't gotten as much interest as before... not sure if this is due to their changed layout or if they've really cracked down on spammers and thieves. Or even if people are generally more scared of using Craigslist due to all the publicity garnered of attacks, killings, etc. If you do make arrangements on Craigslist, meet at a public place - usually a parking lot of a popular grocery store (and not in a crummy area) is best. Just anywhere that there are usually a lot of people around. Or if not, then meet in front of or at a parking lot of a police station, fire station, courthouse, or hospital.
I'd encourage you to do the 'market research' and look at sold listings on ebay as well as current pricing from other sellers of your item(s) on Amazon and Craigslist.
I did have one lady return a Palm Pixi she bought from me because she thought it had a touch-pad and didn't realize it was all digital. Pretty annoying, and I hit her with a restocking fee for the trouble. I have a few phones I need to get rid of but they're not worth much - for me, if the phone isn't worth more than $20-30, I would lean towards just donating it instead. Same thing for the P&S cameras - with the advent of in-phone cameras and everyone moving to prosumer m43/dslr cameras, the value of p&s cameras has steeply declined. Depending on what brand/model the cameras are, you may not get a lot back for them - in that case it may be worth just donating.
Again, be careful will selling the larger and heavier stuff like TVs and monitors. Unless you pack them extremely well and insure them, you're at risk of delivering something broken. It's definitely more of hassle to ship bigger stuff like this - I generally avoid it and try to sell on Craigslist or Facebook.
Speaking of which: two other good resources to sell stuff, more informally, are Facebook and Nextdoor.com. And yes, if your husband has an "internal" CL at work, that would also be great. Any avenue you have is great. Fredmiranda.com is another one especially for camera gear but you can sell other electronics too - there is a fee you have to pay and payment arrangements may vary but it's pretty reliant on using Paypal and splitting fees and shipping costs with the buyer.
Good luck!
