IBM has agreed to buy privately held Isogon to tap into the growing demand for software that automates the way companies manage application expenditures and usage. Terms of the deal, which was announced Thursday and is expected to close in the third quarter, were not disclosed. Isogon's operation <A HREF="http://news.zdnet.com/2100-3513_22-5749512.html?tag=zdnn.alert">will be integrated</A> into IBM's Tivoli infrastructure management software business.