Qball,
As stated below, Airnav.com - http://www.airnav.com/ or SkyVector - http:http://www.skyvector.com. Click on the Airport tab in the upper left, then type the airport name or identifier. Airnav is primarily US and US Territory airports. Will include STARs, IAPs and Departure Procedures, and may have the Airport Diagram in the upper right of the page. Canadian and some Caribbean airport information is included, but do not contain any Standard Instrument Approach Procedures. SkyVector is likewise: US airports include the above procedures; rest of the world has airport information only, no procedures.
These sites work better than the FAAs Digital Chart Supplement site, as the hyperlink changes sometimes during the 28/56 day revision cycle.
You can try VATSIM for non-US Instrument Approaches - https://www.vatsim.net/charts/ There are a lot of broken links, but you may get lucky and find something you want. Google VATSIM and ChartFox (registration required) for additional information.
Be advised: Frequencies do change. The NAVAID database for FS2004 was created almost 15 years ago. If airport XYZ's NAVAIDs (VOR, NDB, ILS, etc.) frequency has changed since the database was developed, you won't be able to fly the approach as now published. Print the procedure you want, then open the FS map during a flight in that area and hover your cursor over all NAVAIDs on the paper chart. Note any changes on the paper chart. If you have .pdf editing software you can insert a text box over the old frequency with the new one.
I have a binder with 25 or so approaches at interesting airports (Aspen, Innsbruck, London City) and others that I use for instrument proficiency.