Okay, there are a few series I've seen that although were really good didn't feel 'complete' to me. I'm going to name the them and ask if anyone knows of any sequels for them.
I My Me * Strawberry Eggs
Very enjoyable series, even if it does go for a double taboo, but the romance story just isn't completed in the series and I do want to see how things are supposed to turn out the few years later.
King of Bandit Jing
Very interesting, and a lot of fun to watch, but it's implied he's on his journey for some special reason, which is neither explained nor completed. There's either a second season, that hadn't been available when I'd been watching the series on DVD from Netflix, or else there is a sequel series.
DNAngel
This one has a someone bittersweet 'ending', but again it doesn't feel like the story was actually completed, just their portion of it.
Elfen Lied
This series felt more like a prologue to a much larger story, a much larger story.
Air Gear
This one felt like more than just a prologue, but still felt as if there was a lot of untold story left to go.
Angel Sanctuary
Sadly, I don't remember much about this one right off hand (almost makes me wonder how it made one of my lists, but it must've been one I felt would be worth watching again or else it wouldn't've made it onto a list), but since it's on my needing sequels list the story probably didn't feel complete.
Master of Martial Hearts
Come on, this one does a great job of establishing a good setting, and even sets up a good story for the setting, but that's all it did, where's the rest? It's barely more than a prologue.
The Sacred Blacksmith
This one also clearly didn't have a completed story. Think more like the first couple chapters of the first book of a duology or trilogy.
Queen's Blade
Well, since I'd watched this one I've learned that there is a large 'game setting' that the anime is based on, and that the anime might not have been meant to be a complete story in its own right, sort of like Star Ocean EX, but if there is a sequel to it out there some where I'd love to know about it.
Well, that's all of the ones I've seen that I feel are in need of sequels. If anyone knows of any sequels to these I'd really appreciate being informed. Also, if there are any series that you are trying to find a sequel to then you might as well use this thread as well, I might've been to lazy to look for one, but I'm hoping that this one will stay near the top long enough to be helpful to me and others for a while.