Microsoft Security Account Manager (SAM) Remote Protocol has a way to map 7 bytes to a DES key, similar (possibly identical) to the question's "concatenating the 7 bit chunks together, left to right (big-endian sense)".
One way to see it is that the key bits are laid out on a line, by increasing indexes of bytes and within that in big-endian order (that is, key bits are laid out by increasing bit number per DES specification, since that numbers high-order bits with the lowest number), with the low-order bits in the $8$-byte form (that is, bit number multiple of 8 per DES specification) discarded in the $7$-byte form, and regenerated when going from $7$ to $8$ bytes (as a zero bit, or perhaps using odd parity).
Otherwise said, with $1\le j\le7$, the $j$th byte in the $7$-byte form has its $(8-j)$ high-order-bit(s) mapped to the $(8-j)$ low-except-lowest-order bit(s) of the $j$th byte in the $8$-byte form, and its low-order $j$ bit(s) mapped to the $j$ high bit(s) of the $(j+1)$th byte in the $8$-byte form, with no reordering of bits within each of these two segments.
As far as I know, this is not standard in any other way than having been used by some widely deployed operating systems. Also: using this convention makes it rather messy to implement the first key transformation in DES, named PC-1, starting directly from the $7$-byte form of the key; when the different convention described in poncho's answer can be viewed as being PC-1, easing a software DES implementation.