Vircurex is an exchange for crypto-currencies just like Bitparking or BTC-E. Therefore it's a platform that enables you to trade (buy, sell) your BTC for - let's say - NMC, LTC or even USD and EUR and vice versa.

There's nothing "mining related" to it, besides that it seems quite a few miners use it to dump their merge-mined Namecoins now and then.

Pro Vircurex:
- it has all the relevant crypto-currencies
- support for USD and EUR
- clean and simple UI
- ability to trade options

Contra Vircurex:
- it really has no market depth/volume

That's only one "contra", but it made me move away for most of my trades. I don't want to wait a day or two before finding a fitting counterpart to my trade. If that would change, I'd recommend VCE without a doubt.

Hope that helped a little.

Cheers!
  ~drekk~