On Dota 2 Lounge players can trade their Steam Dota 2 items with others. You can create offers and define what you want to have for your stuff.
Dota 2 Lounge Trades
You can place offers by yourself, or check what other people got. The Offers differ a lot, and you should always check if it’s no scam or a trap. Here is a Screenshot of an offer. As you can see often random things of a common value like “rare” are traded for something else. Always compare the values and trade with caution.
Dota 2 Game Bets
On the page you can also bet on live games. Via twitch.tv the games are directly accessible next to the bet. Betting is hard, but placing on the underdog can bring good income sometimes. 😉 Try it out!