Hallo :
I found that adbrite are using 10 name servers .
asia3.akam.net
aus1.akam.net
eur1.akam.net
eur2.akam.net
ns1-105.akam.net
ns1-232.akam.net
ns2.adbrite.com
ns4.adbrite.com
usc2.akam.net
usw6.akam.net
could any one has for example 3 hosting accounts each one in
a ddifferent hosting company , could it be possible to put all Name Servers
of 3 different hosting sites under one domain name ?
what could go wrong ?

You do not need to do this - make sure your host is using a redundant dns setup or get an external dns like dnsmadeeasy or free like zonedit etc.
Make sure everything is setup correctly - especially all nameservers should return the same SOA (that it would be difficult if you use the nameservers of 3 different hosting accounts and you do not have access to the zones).
As for adbrite, it is not so well configured:
http://intodns.com/adbrite.com

do you think this could help solve the problem of limited bandwidth .
any ideas ?

The bandwidth of DNS is MINIMAL.