Cryptocurrencies are a good market for speculation, and a risky long term market but that could pay off big time.
I know someone who made a bit of money off bitcoin, and I've been following the market for a while (haven't invested in it, though I mined a little). At every point people said it's not worth investing: when it was $15, when it was $40, when it was $100, ... The bitcoin has yet to show any sign that it's a bubble that's about to burst. Sure it varies wildly in dollar value, but it keeps going up on the whole, and it still has a way to go up. The more places accept it, the more countries accept it, the more it's likely to go up. Of course, countries banning it will make it go down. That's why it's risky, but on the whole it still has potential to become a lot more valuable.
Alternate currencies are mostly bullshit, except for litecoin. Litecoin is the only other one that's directly convertible to dollars, and if it does catch up to the bitcoin in terms of use (such as Mt. Gox trading it, which has been rumoured), then it could go up. Also scrypt mining hardware (scrypt is the algorithm used for litecoin and most other currency) should be out this year and might raise prices. The rest of the coins are mainly a way to gain a short term mining advantage, and are extremely unstable. They are easily exchangeable through trading sites such as Cryptsy.
As for speculating, both bitcoin vs. dollar and bitcoin vs. litecoin go up and down significantly enough that it should be possible to make some money with buy/sell orders. Not tons of money, but if you like this kind of thing you can probably invest enough to make it worthwhile.
Generally the best dollar value for bitcoin is at Mt. Gox, but I've heard that it's not that easy to actually get the money from Mt. Gox.
The short of it is, if you like playing with investments (it seems that you do) and you don't mind a bit of risk, cryptocurrency is a very interesting market. If you have an Android device, you can install Bitcoin Checker and get an up to date picture of currency prices vs. other currencies at various markets, set alarms based on conditions (reached certain value, went down a certain percent, ...) and generally lose your life to cryptocurrencies.
Post edited February 04, 2014 by ET3D