Any business that accepts Bitcoin can be paid with XMR.to which automatically converts Monero from the buyer into Bitcoin that will promptly be sent to the Bitcoin merchant.
Shapeshift.io offers a similar service to xmr.to but with slightly slower payments (they wait for tx confirmations instead of scanning the mem pool like xmr.to) and much lower maximum ...
You are probably referring to XMR.to, a website that allows people to make anonymous payments to a Bitcoin address with Monero.
XMR is the trading symbol for Monero, which is why the domain is relevant.
You can learn more about BinaryFate, one of the founders of XMR.to, in this podcast.
The website has no registration. However, they log your IP address. ...
I am not aware of any warrant canary existing at the moment.
Monero (unlike ZCash and Dash) doesn't have any central authority - an organisation, that could receive the subpoena secret order or equivalent. Each node in network is equal to the rest of nodes and nodes are running opensource code that is developed in the open on GitHub. Multiple people monitor ...
To add to expez's answer, BitPay should already stop the 15 minute countdown once it's found the broadcasted Bitcoin transaction.
To my knowledge some services that use BitPay require confirmation(s) but it shouldn't be an issue as the invoice shouldn't expire after the tx has been broadcast (but not yet confirmed).
IIRC xmr.to scans the memory pool, so they can send the transaction ASAP, without waiting for a block to be mined, so they're not going to be the bottleneck here.
That being said, remember that blocktimes such as 10 mins are target values. The time to mine any specific block is random. Sometimes it takes 20 minutes to mine a Bitcoin block, sometimes it ...
Note that if you access it on its onion address at http://xmrto2bturnore26....
XMR.to has slightly lower exchange rates (usally around 1%) than the big exchanges, but even for small payments they cover all Bitcoin onchain transaction fees and their transactions usually will be included in the next Bitcoin block so they have a pretty good fee estimator and/or are well connected with Bitcoin miners.
When creating a new payment on xmr.to ...
XMR.TO admin here.
I do not know where you saw that XMR.TO does not charge a fee in general, this is not true and to the best of my knowledge we never made such statements.
However it is true we do not charge anything on small orders. The reason is that, unlike all competitors, we are a Monero-specific service: we launched in 2015 for both building a ...
There are currently no wallets with native XMR.to integration. This is, however, planned for the official GUI at some point in the future.
EDIT 12/25/2017: Monerujo, a third-party Android wallet, currently has native XMR.to integration1
XMR.to started as an instant, no-signup, non-KYC Monero to Bitcoin exchange but has since grown to include some more services, including:
XMR -> BTC exchange
Public nodes, including Testnet/Stagenet and Tor nodes 
An API for creating exchange orders/viewing price 
Block explorer 
Testnet/Stagenet faucet 
Network node map 
Aeon (Monero fork) ...
Your analysis is correct, however knowing that the transaction is one of the five transactions (in average) of a block will not help to identify your address as it will be one of the 5*7=35 addresses of the lot used as ring signatures.
Let's say it is possible to guess the exact Monero transaction on the blockchain that resulted in the corresponding Bitcoin transaction.
That would not constitute a significant privacy leak. No one can know your Monero wallet address or even which outputs you were actually spending.