There are always ways, but it will still be apparent to your IT department that you are going to these sites or that you are trying to circumvent their blocks, which could result negatively for you depending on the acceptable use policy that you signed. The best way is to talk to your IT department and ask nicely for them to enable access to the sites that you need, or even to ask them to stop restricting access to anything that isn't obviously malicious (our IT department recently opened up access to almost everything except obviously malicious sites after a similar conversation).