(Editor’s note: Dharmesh Shah is a serial software entrepreneur and the founder and CTO of HubSpot, which provides marketing software for small businesses. This column originally appeared on his blog. )

I’ve been in the software startup business for a long time – long enough to spot a few trends. One I’ve found particularly interesting is that amongst first-time software entrepreneurs, certain “patterns” of applications kept recurring.

Time and time again, entrepreneurs are lured to one of 10 application categories.  It’s not always a bad thing, but it’s certainly curious. Here’s the list:

Project Management / Time Tracking / Bug Tracking – This is likely because the developer had to work at some point with existing software that just sucked and thought “Hey, I can build something better in a weekend and it will do exactly what I want.  It’ll support custom fields, and query-by-example and persistent views and all sorts of neat stuff.”

Community / Discussion Forums – The developer/entrepreneur was perhaps kicking off a new online community for whatever hobby area she was interested in and began poking around, looking for something to meet her needs, but saw nothing appealing.  “Hey, this is easy,” she might have said. “The data model is trivial and I can use this project to learn about this new web framework I’ve been meaning to play with.”

Personalized News Aggregation/Filtering – I’m not exactly sure why this one keeps cropping up.  I think the reason is that it seems obvious that there’s just much more information out there than any normal person can consume.  The entrepreneur arrives at some interesting angle on how to better filter the information, whether it’s individual voting/learning mechanisms or social features (i.e. your friends liked this stuff, so you will too).

Content Management (website, blog) – Another one of those seemingly simple apps (“how hard could it be?”) combined with the fact that it’s often harder to learn some existing system and make it do what you want than just hacking together a “minimalist” application (that over time, becomes less and less minimal).

Social Voting and Reviews – This one’s newer to the scene.  These applications allow users to vote/rate/review something (movies, books, wines, whatever).

Music/Events Location Application – What the world really needs is a way to figure out when their favorite band is going to be in town.  Connect with your friends!  Figure out where they’re going!  Hook-up! It’s a guaranteed winner, right?

Dating and Match-Making – This one requires no explanation.  As is the case with most of these application categories, entrepreneurs often like to “scratch their own itch”.

Personal Information Management -I think this one is really common because it’s often one of the early applications developers build to learn something new.  “Hey, I can use this new ORM system to track my DVD collection.  It’ll take just 50 lines of code!”

Social Network For ______ – These were happening well before MySpace and Facebook.  In this case, the application is not completely trivial — but that’s what makes it a bit more tempting.  The data models can be rich and if one has some UI chops, it’s often a fun application to work on.

Photo/video/bookmark/whatever sharing – As humans, we like to share stuff.  The appeal of this application is it’s broad appeal (hey, my girlfriend needs a way to share her photos from her recent trip to Brazil).

Don’t get me wrong; I’m not saying that building an application in any of these categories is doomed to failure.  I just find it curious that these specific themes tend to occur again and again.

Did I miss any?  Which application categories do you think entrepreneurs are lured by?  And do any of you just happen to be working on a fun little project that falls into one of these categories?