Recent Post Widget With Thumbnail and Tooltip For Blogger

1. Blogger > Layout > Add Gadget > HTML/JavaScript
2. Add the following code in it and Save it.

<style type="text/css">
#post-gallery {
  width:304px;
  margin:0px auto;
  font:normal 11px Arial,Sans-Serif;
  color:#494848;
  padding:8px;
  background-color:#17B986;
  -webkit-box-shadow:0px 10px 30px rgba(0, 0, 0, 0.4);
  -moz-box-shadow:0px 10px 30px rgba(0, 0, 0, 0.4);
  box-shadow:0px 10px 30px rgba(0, 0, 0, 0.4);
  -webkit-border-radius:4px;
  -moz-border-radius:4px;
  border-radius:4px;
}
#post-gallery h2 {
  font:20px Arial,Sans-Serif;
  color:white;
  text-shadow:0px 3px 2px black;
  text-transform:uppercase;
  margin:2px 2px 2px;
  padding:7px 14px;
  background-color:#48D;
  text-align: center;
}
#post-gallery .rp-item {
  float:left;
  display:inline;
  position:relative;
  margin:2px;
  padding:0px 0px;
  background:#fff url('http://softglad.at.ua/images/loading.gif') no-repeat 50% 50%;
  width:72px;
  height:72px;
}
#post-gallery .rp-item img {
  width:72px;
  height:72px;
  border:none !important;
  margin:0px 0px !important;
  padding:0px 0px !important;
  background:transparent !important;
  display:none;
}
#post-gallery .rp-item .rp-child {
  position:relative;
  top:10%!important;
  left:10%!important;
  z-index:1000;
  width:200px;
  background-color:white;
  border-top:5px solid #FA7C19;
  -webkit-box-shadow:5px 5px 10px rgba(0, 0, 0, 0.7);
  -moz-box-shadow:5px 5px 10px rgba(0, 0, 0, 0.7);
  box-shadow:5px 5px 10px rgba(0, 0, 0, 0.7);
  padding:10px 15px;
  overflow:hidden;
  word-wrap:break-word;
  display:none;
  opacity: 0.9;
}
#post-gallery .rp-item .rp-child h4 {
  font-size:12px;
  margin:0px 0px 5px;
  color:#FA7C19;
}
#post-gallery .rp-item:hover .hidden {display:block;}
</style>

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.8.0/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript">
var rpTitle     = "Latest Post",       // Widget Title
    numposts    = 20,      // The number of thumbnail / posts to display
    numchar     = 200,      // Number of characters in the description tooltip
    rcFadeSpeed = 600,      // Speed of the effect. fadeIn () tooltip appears
    pBlank      = "http://softglad.at.ua/images/no-img.png",      // Image that show up if the post doesn't have a image
    blogURL     = "http://www.a2zhackers.com";       // Your Blog Address
</script>
<script src="http://softglad.at.ua/widgets/post-gallery.js" type="text/javascript"></script>

Replace http://www.a2zhackers.com with your blog url. numposts is the number of thumbnails / posts that you want to display. numchar is the number of characters in the description tooltip. rcFadeSpeed is the speed of the fade effect.