OCPWannabe may be right on this one.
rule 1 : no - one's indispensible.
I am also in a simiar position to yourself. Have taken on lots more responsibility on Oracle Database and have also been given SQLserver responsibilities and Unix Admin responsibilities. I am also the only Oracle 8i Guy in the company.
I was not treated in any way special or even thanked for my years work.
I am pursuing 8i OCP at the mo' and should have it in February. I will then confront IT head with a pay rise request. If I don't get any joy he'll know my intentions.
UK is not doing too badly for Oracle skills demand check http://www.jobserve.co.uk.
rule 2 : always keep your options open.
Once you have eliminated all of the impossible,
whatever remains however improbable,
must be true.