Below is a chart of retirement plan contribution limits showing historical contribution limits from 2002 to 2006. SEP IRA, Profit Sharing and Money Purchase Plan maximum contribution or Keogh have the highest retirement plan contribution limits, followed by 401k, 403b, and Section 457 retirement plans.
Retirement_Plans_Contribution_Limits.html
If you have multiple IRA acccounts, you can make multiple IRA contributions. The examples below illustrate how you can make multiple IRA contributions.
Multiple_Contributions.html