Blogger recently add this in widget section you can add this from widget section. To add Label Cloud or Tag Cloud, go to admin section by login blogger by your google or gmail account. Click layout add widget, when you click this link a popup window will appear, scroll down to see Labels, Click this you will setting page, here you can set values of label cloud like if you want to change Labels into Tag Cloud or Label Cloud. You can show all labels or only selected ones. Sorting the labels by alphabetically or by frequency, now at the fourth point Display you have to mark cloud. At last step mark if you want to show no. of post per label or unmark if not want to show post no. This widget has main problem you can not change color of labels, it sticks with sidebar text color, if you want to change the color of tags then you have to add it through template for code and method see this post.