How can I put a collage of pictures on my wall without tape?

I want to put a bunch of pictures on my wall like these: a href="http://jurickphoto.blo.com/2009/05/cool-heart-shaped-collages.html" rel="nofollow"http://jurickphoto.blo.com/2009/05/…/a but not in heart form. just everywhere. i've tried putty and tape, but since my walls aren't smooth and they have a texture to it like this: a href="http://www.google.com/imgres?imgurl=http://www.bobvila.com/images/ArticleImages/TexturedWalls_01.jpg&imgrefurl=http://michaeldunncenter.org/g/view.php%3Fq%3Dplaster%2Bwall%2Btextures&usg=__Lr3C1a4hS68DM-uvU1lPjuty7Xw=&h=240&w=240&sz=13&hl=en&start=0&zoom=1&tbnid=gdtpFF0qc0fHoM:&tbnh=137&tbnw=137&ei=MVcxTbCHGYKr8AawxNnSCA&prev=/images%3Fq%3Dtextured%2Bwalls%26um%3D1%26hl%3Den%26biw%3D1280%26bih%3D709%26tbs%3Disch:1&um=1&itbs=1&iact=hc&vpx=259&vpy=220&dur=1457&hovh=192&hovw=192&tx=138&ty=161&oei=MVcxTbCHGYKr8AawxNnSCA&esq=1&page=1&ndsp=19&ved=1t:429,r:1,s:0" rel="nofollow"http://www.google.com/imgres?imgurl=http…/a , its very hard for the pictures to actually stick. So any ideas?! I don't know if I want to staple my pictures because I'm gonna be probably stapling around 150 pictures on my wall and I don't wanna leave marks. So any helpful ideas?!