Here are a couple of layouts where i've used a simple watercolouring technique (aka, making a big inky mess). This layout was one i created whilst taking the Art + Design Class with Wilna Furstenburg. She has created some fantastic pages using gelatos & is the main reason that i wanted to try them out in the first place. In fact, she covers them in both of her Art Classes which i can highly recommend.
photo credit: onethousandwords.co.uk
On this one i used watercolour paper so i didn't need to use any gesso as a base. It's much easier to do this technique on watercolour paper so i recommend starting out using that if you're just learning.
And here's a layout where things didn't go quite right. The colours turned out a LOT brighter than i thought they would. It might have been wise to experiment on cardstock first...but i didn't. Lesson learnt. It's still going in the album though, because you know, i'm brave and wild like that ;)
Have you used Gelatos yet?