There is a pretty useful trick that twitter insiders use all the time called a hashtag. The roots of the #tag are buried somewhere in IM coding, but it’s what you can do with it using twitter that matters. (More on hashtags if you want to techie stuff on this.)

The hashtag or #tag added to a tweet acts as way to create categories, groups or topics for tweets that others can use as well. This way, tweets can easily be grouped together using the search.twitter.com feature.

Let me give you a very commonly used tactic for this. Let’s say a group of folks are attending a workshop and tweeting their notes in real time. If everyone at that workshop were asked to add something like #mkt101 to their tweets, everyone present or not can see and share all the notes in one place.

During earthquakes and fires hashtags are a great way for people to get news.

Promoting events and product launches via a hashtag helps keep the word in context

Companies often use hashtags as a way for remote employees to use twitter as a communication tool for all the stuff people should stay on top of.

I use a hashtag for each of my live webinars and then people tweet and ask questions via twitter and I have a back channel of conversation and notes and another source of relevant content to support the webinar.

You can also find hot trends via hashtag at search.twitter.com. The homepage lists the trending tags. More than one twitter user has found that jumping into a hot trend conversation is a great way to connect with folks on something of shared interest.

Anyone can create a hashtag by putting # in front of anything. Keep is short so you don’t use up your 140 and try for a little unique. If you use a tag that others are using you will mingle your results with others.

Here’s an example of a search for the hashtag I used during the call with Seth Godin last week – #dtmseth