Obviously, the value of any coin can vary, depending on its condition - and also on the demand there is among collectors of such coins. However, there are a number of ways in which you could establish the value of your Queen Victoria 1900 penny coin.
According to my research, there were approximately 32 million of these particular bronze penny coins minted in 1900.
Valuation sites seem to peg the value of each coin at somewhere between half a dollar, and three dollars, depending on condition (these figures are from early 2013).
See this link to view my source.
The 1900 penny features Queen Victoria on the front, and Britannia on the back. The latter is holding a trident and shield, apparently to symbolize Britain's mastery of the seas and its empire.
The inscription on the coin, "Victoria Dei Gra Brit Regina Fid Def Ind Imp" means an abbreviated version of, "By the grace of God, Ruler and Queen of Britain, Defender of the Faith, Empress of India".
Other ways to find out the value of old coins
eBay is always a good place to start when you wish to see how much other people are willing to pay for something, at any given time.
If you're not already a member, then you could sign-up (for free), then add auctions of similar coins to your "watch list", which means that you'll then be able to see whether each coin sold and, if so, how much for.
Another good place to try would be one of the numerous coin collectors' websites, where members can join discussions about coins on a variety of forums, and find out what values certain coins are fetching.
I've listed a few sites with links below, and hope this helps!