Have you noticed how the size of external SSD drives has been dropping? About a year ago I started switching to Lacie external SSD drives (Memory that just look like disk drives) because they are so fast and they don't require their own power. They are just powered off their USB or Thunderbolt cable.
A couple of weeks ago I discovered the newest generation of SSD drives. The Samsung T3 Portable SSD. My first reaction was disbelief. How could you get 500 GB in such a small package? They are literally about a half and inch shorter than a credit card and 3/8" thick. They are amazingly fast - read-write speeds of up to 450 MB/s. And reportedly very reliable. They come in 250 Mb, 500 MB, 1 TB and 2 TB. For use on a laptop, they are awesome. I have a 500 MB and a 1 TB and I love them. Here is a more in-depth analysis.