Is there a website or service that can quickly lookup how much bitcoins are there in a given wallet/address, so I can look up my own wallet from a friend's computer which doesn't have the Bitcoin client installed?
You can use Blockchain.info.
Just paste the address you want to check into the Search inputbox and the website will show you all the transactions where that address was involved, as well as the balance.
In Blockonomics you can search multiple addresses of a wallet at once. It also has a wallet watcher where you can enter multiple addresses and get the overall balance in btc and currency of your choice. You can also see history of tx
protected by Bitcoin Nov 26 '15 at 3:06
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