I just installed the cbnet Twitter Widget plugin last night and I love it! It's the only one I found that allows me to do a Twitter search easily (username filtered by hashtag). It's simple to install and flexible to configure.
Except.... That extra
<br> at the end of the widget in the sidebar!! It's forcing an unnatural amount of space below the widget in my sidebar, and since it's in the markup, I cannot remove it. To make extra spacing by default below the widget, I think you should do it in the CSS instead of in the markup, where we can override it.
FYI the blog is here, to show you what I mean: http://faithwilson.org