I've been loving Tim Holtz line of Distress Inks by the parent company Ranger. They're alcohol-based dye inks that are great for blending and allow for creating an "aged" look on paper, shadowing, stamping, etc. I use them primarily to ink around edges and my handful of Distress ink pads have become staples in my crafting! In the above set of cards, I used Vintage Photo Distress Ink. I used Vintage Photo in the card below, as well.
In order to use the ink to blend along the edges of paper, I use the Ranger Inkssentials Ink Blending Tool and Foam. I used to (and sometimes still do) use a piece of a dry kitchen sponge. It's not as convenient as the blending tool, but it does lend a more rustic-looking and rough effect. All the products mentioned can be found on the Ranger Ink website: http://www.rangerink.com/products.htm
The above image is from www.thecropstop.org
For more information about how to use Distress Ink, there are plenty of tutorials on YouTube!