This site displays bitcoin transactions in real time. On the red and purple line all transactions below 1 BTC are mapped.
The middle circle expands on transactions above 11.4 BTC (~100 000 DKK or ~14 000 USD). It will glow red on transactions above 114 BTC (~1 000 000 DKK or ~140 000 USD).
Bitcoin is a virtual currency. It relies on a peer-to-peer network, which mean that users can transfer money without the need of banks. Each transaction is public to ensure that it can be verified by other users.