Links that we found usefull when developing our products:

EFG's Computer Lab
Index of available math resources for Delphi

Inovative Integration

Suppliers of DSP, data acquisition and industrial control solutions. 

Steema
Home of TeeChart and TeeTree VCL components. The main charting tool for Delphi and CBuilder users. 

Available C++ Libraries Frequently Asked Questions List
The largest list of available commercial and free numerical software for C/C++. 

Netlib Repository
Netlib is a collection of mathematical software, papers, and databases. The site features the largest collection of numerical code in fortran. 

Decision Tree for Optimization Software
How to select an optimization method and where to find free source.