National Geographics from the 1960's are worth nothing:
http://uttm.com/stories/1999/03/18/deleted/main39419.shtml
I would ask your local library if they want them to complete their collection -- if not, recycle them.
For all of the other items, you can generally list them for free on http://www.craigslist.org -- you may need to renew the listings a few times.
Many people have warned against using eBay and I have to disagree. The beauty of eBay and other on-line auction sites is that you have a GLOBAL set of buyers instead of just the people from the surrounding couple miles who show up at the flea market or read the pennysaver. You can have a minimum sale price you will accept if you don't want to let things go too cheaply. You get to re-list most items for free if they don't sell. Etc.
Record Albums: There are lots of people who collect the old vinyl LP's, 45 RPM singles, and so on. Value will depend entirely on what specific album it is. You are going to have to type in each and every album 1 at a time into the search engine to find out what they are worth. You might have luck through one of the vinyl LP collector groups:
http://www.solidviper.com/
http://www.vinylrecords.co.uk/
http://dmoz.org/Arts/Music/Collecting/Vinyl/
As a hint, start by alphabetizing them by artist name, so you can look through whole lists on-line faster.
The good albums put up on eBay or sell through a specialty vinyl LP dealer. The rest put in a box and give them to someone at a flea market who is already selling vinyl LP's.
Old Atari games: Very sale-able. Put them up on eBay, individually but be willing to "combine shipping for multiple wins". Make sure the listing says they are NIB (New In Box) Unopened. If they are for the Atari 2600 look here:
http://games.groups.yahoo.com/group/atari2600/
If for a different Atari platform, just type in "Atari _____ game group" into the Yahoo search bar and you will find enthusiast groups. As you can see by the following eBay search, these things can fetch a decent price:
http://search.ebay.com/search/search.dll?cgiurl=http%3A%2F%2Fcgi.ebay.com%2Fws%2F&fkr=1&from=R8&satitle=Atari+2600+games&category0=&submitSearch=Search
Video Discs: Again, there are collectors out there. Not as many as for video games, but they are there.
http://search.ebay.com/search/search.dll?cgiurl=http%3A%2F%2Fcgi.ebay.com%2Fws%2F&fkr=1&from=R8&satitle=Atari+2600+games&category0=&submitSearch=Search
Here is someone with specific wants:
http://puosu.dna.fi/~kerappo/ld/ld-want.html
Craigslist is a very good place to advertise these, it is global but can be narrowed to local listings to avoid shipping, and it is free so you can afford to wait for the few interested buyers.
For the skiis, contact nearby high schools and colleges -- most have a ski sale each winter. Failing that, these are good items for the pennysaver.
Knick nacks -- again, good eBay items if you know exactly what they are. But if they are just "this knick nack thing" then it will be very hard for buyers to find your listing so eBay probably will not get a good sale price and may cost you money in the long run. Your local flea market would be better.
Crystal, China, and colored glass -- these can be very valuable, or hardly worth anything. You need to have MULTIPLE antique dealers or specialists look them over. Don't just take the first dealers word for it that they are only worth a couple bucks. The number of people on PBS's "Antiques Roadshow" who get their whatsit appraised at $100,000 after the local dealer offered them $100 for it is stunning... These are the kinds of things you really need to research and learn about to not get taken.
My condolances on the loss of your husband.