Actually, how big was it in 2006 (now it's even bigger, but we don't have the numbers).
Ebay marketplaces (including StubHub, Rent.com, and local classifieds): $4.3 billion
Paypal: $1.4 billion
Skype: $195 million (up 686%)
Total annual revenue : $5.895 billion
Let me repeat: $5 895 000 000 - that's a lot of zeros...
If eBay was a country instead of a single company, it would rank 131th out of 180, ahead of Nicaragua, Haiti, Mauritania and Rwanda. Check full country listing by GDP.