so i'm trying to make a model, and for simplicity lets say its a tic-tac-toe shape =P
4 edges are made, and layed so  it looks like a tic-tac-toe board, but my question is
how do i made a vertex at each of the points that the edges intersect?

I think for me the fastest way would just be to loop cut each line, eyeball it as close as possible, and then merge the vertexes. 

I just looked at using a boolean op, but it doesn't see to work well for just edges. 

If someone else has a better method, I'd be interested in hearing it as well. 

Good luck.

id say use the multi cut funtion om multiple lines at once.

I got this from searching at BlenderArtists forums.

Geom Tool : it makes geometric operations (intersection, projection ...).
http://www.hybird.org/~guiea_7/scripts/geomtool.zip

thx thats handy tool does it work ok?

Trying this out at the moment. Aligning verts works fine and as expected but it looks like when doing alignment to face or edge, if you select a face or edge and multiple verts, it keeps asking you to select an edge. If you just select an edge/face and a single vertice it works OK. I may be not be using it properly though. For me, the vert alignment option is worth the installation, better than other systems I've tried.