You can still donate organs and blood, but you will have to wait for a period of 12 months if you live in a state that does not regulate the tattoo industry. This is to ensure that you have rid yourself of any possible infection, or that you know about any possible communicable disease that you may have contracted. These circumstances are very rare and you should be able to donate blood without trouble.
If your state does regulate tattoo parlors and require health inspections, you may not have to wait nearly as long. Check your local regulations and blood banks to find out.
Thanks for caring enough to be a donor!