BWeld is a Free Script That creates welds at intersection, (like Joker Martini 's Welder for 3ds Max)
-Just put bweld.mel in Documents/maya/maya_version/scripts/
-And attach this to hotkey(runtime command)/shelf : source "bweld.mel";
-New Feature : Flat Fillet, generate a loop of polygons that serve as a fillet or a decal on which textures (weld textures) can be applied.
: you must choose between rough weld and flat fillet, now.
-it can fail on some extreme cases, but will work in most situations
Other free things :