I'm working on a program for D&D. Right now its just a character sheet program with some fancy extras of my own design thrown in and later I'm going to include DM tools with it.

I was wondering if this is legit to post under the "Under Construction" thing since its not really a game, but it is game related and I am the one making it.

I'm not sure what you mean by "Under Construction". Do you mean post in the Project Showcase? In order to post anything game-related, you must post through the "Submissions" area where it must be approved before moving out to either Project Showcase, Project Demo, or Completed Games. There are templates for each area that state what the minimum requirements are. In most cases the minimum requirements are:

Story
Character Bios
Credits
Screenshots
Features

Ah, yeah. What use to be under construction.

I suppose all I could fulfill of that is credits, screenshots, and features, since it isn't actually a game.

Is it something that others can use as a resource?
If so, you can put it into the Resource Submissions forum.

I suppose they could. Its focus is for making D&D character sheet, but I'm planning to add in DM tools later which could have some useful things for people designing RPGs as well as D&D campaigns.

Should I wait until its complete or can I post what I have now, like screenshot's and info. I really want to get some new ideas for it mostly is why I'm asking.

I believe it would be fine to post it up as it is in the Resource Submission area - as an ongoing resource, it might attract enough attention to get some ideas from other members and such. ^^