There is a currently a spam attack on the network. While we "normaly" have up to 6000 transactions waiting for a confirmation durring prime time, we now have over 60k transactions waiting for a confirmation constantly, at least for the last week. The private key you (and others) found was used in the spam attack, among ~100 other keys and possibly more I dont know about. The funds that are associated with those private keys are of 1000 satoshi each.

Now if you want create a bitcoin transaction it consists of inputs which refer to a previously received transaction. In this case you would refer to those 1000 satoshi transactions (~450k have been confirmed a few days ago) that have been received in the past. Each input uses ~180 bytes and the fee one would normaly use is 10,000 satoshi per 1000 byte. As you can easily see you can only use 5 inputs of 1000 satoshi each if you want to stay below 1000 bytes. 5000 satoshi however is considered a low fee and you would not even send any coins anywhere. Thats why these are next to impossible to spend. Some big mining pool is currently working on a clean up AFAIK as they can just put their own TX into their own block. Everyone else cant really do much about this as paying a higher fee would require you to use more inputs which in turn increases the size which again requires a higher fee to have a chance to get a confirmation under the current circumstances.

I've had a few of these in the past, only ever to my blochchain wallet i have noticed.
I never use this wallet anymore but still check it from time to time and find a tx for 0.00001 with some spam advertising.

They are just wasting there money and our time.

That's right i couldn't think of the name.
I received about 5-10 transactions from them with the same tx header.

There was thread here on BCT about it when it was all happening.

Isn't the spam attack over already ? Thought it was only 2 weeks back and not happening any more. I don't see transactions taking time to confirm anymore either.