If you are looking for a relatively small amount of silver, a few ounces here or there, the best place is probably your local coin shop. Acquiring it is pretty easy, just walk in, pay cash, walk out with silver. Your pre-1965 US coinage (90% silver) is a very good start and a good thing to have; nothing wrong with getting some more of it. You can buy silver online from dealers like APMEX, Provident Metals, Midas Resources, Tulving (if you want A LOT of silver), Scottsdale Silver, Eastern Numismatics, and countless others - this list is just what popped into my head. You can also find silver on ebay, craigslist, coin collecting message boards, and coin shows, where you can often find items at or near spot price (sometime less!).
Other common forms are 1 oz coins from major government mints, like American Silver Eagles (ASE) and Canadian Silver Maples, or generic silver from well known private mints like NTR, APMEX, and the like. Coins like the ASE and Maples will carry a higher premium than the generic coins and bars, so you get more silver for your money with generics. The coins from government mints have very good reputations and are considered highly trustworthy, and therefore carry a higher premium.
Also, the larger the unit of silver your buy the lower the premium will be. So, buying one 10 oz bar would be cheaper than buying ten 1 oz coins. That being said, many sellers will give you a lower rate based on your total order, so you could buy the ten 1oz coins for the same premium as the 10oz bar if you buy them all at the same time.
I would take a look at the APMEX website since it is pretty well done and easy to navigate and see the different options:
http://www.apmex.com/Category/503/Silver.aspx
Their prices, when shipping is added, aren't a steal and you can find things for less. Most of the time my local coin shop is less since there is no shipping fee. It is a good place to look at what is available.
I wasn't sure exactly what kind of information you were looking for, so hopefully this helps you our and sorry if this is a repetition of things you already know. pmbug.com has a lot of good info for getting into precious metal acquisition/investing.