Buy a licence of Helvetica. Problem solved.
If you arre on a Mac, Helvetica is a system font. Therefore legal to use in commercial work.

You could license a legitimate version of Helvetica or Neue Helvetica as required. Better yet, you could license the digital revival of Neue Haas Grotesk!

It is worth noting that a standard license will only cover you for traditional print publication and not any kind of commercial digital distribution that requires embedding of the font data. However, some digital platforms have versions (certain weights/styles) of Helvetica available as system fonts that can be used in those scenarios. Outlining is another option to consider.

You may also find the discussion of Helvetica in this thread of interest.

ok thatks alot for you answers i really a preciate it, eaven though i allready new that was gonna be the answer, so here are some more specific questions:

1. one of the problems am having now is that my client wants to modify the "A" in helvetica font, and eaven if i try getting a helvetica clone i know its gonna be impossible to find one with the modified "A" as he requires; basically he wants the hummmm... "A" that you can find in century gothic thats like just the cricle and a stick (can really remeber what its called,) so hes on my back about this and i cant seem to find a solution, i dont really wanna have to go trough all the problem of printing/scanning/tracing/kerneling... etc etc etc.

2. gray areas.... i know its not etically or morally corect but.. it there any way i can modify the helvetica font without having to purchase it or make my own?

am really limited here and in a hurry cuz this project gotta be finished by november so any help is really apreciated... lika say..... someone owns a clone helvetica they wanna let me modify?? hahahah

You might want to check the license associated with the Adobe version...

http://new.myfonts.com/fonts/adobe/helvetica-neue/

Adobe's font license has traditionally allowed modification.

If you don't need anything fancy, there are, of course, the Nimbus Sans L fonts available with any Linux distribution or through the Ghostscript project. These are free software and allow modification.

st

Just as a by-the-way, the academic journal boundary 2 is set in Helvetica.

http://www.dukeupress.edu/Catalog/ViewProduct.php?productid=45602

Nimbus-Sans-based Helvetica look-a-likes:

NimbusSanL (AFPL)
FreeSans (GPL)
TeX Gyre Heros (GFL/LPPL)

All are freeware or freely available.

Even if you manage to become legal in the eyes of the Law, using Helvetica
for a long book will remain totally illegal in terms of typographic decency.

hhp

@hrant - Now that is a whole different forearm.

@marosteeha - Didn't remember last time, but OSPublishing's Limousine, which is a hacked Nimbus Sans, has that one-story (bowl'n'stick) 'a' already. Useful as a pattern, if nothing else.

Why not use Utopia, as it is a "square-ish", neutral serif?

There is a reworked Version of Utopia, based on the free 1992 Version:

http://code.google.com/p/evristika/

Used by many newspapers.

As is Venturis ADF.