Symbols.com is a great resource for anyone interested in including personal symbolism in their textile practice. This site is also great for anyone doing research into the motifs and designs found on historical textiles or ethnic textiles.
This site has categorized over 1500 symbols in a thesaurus like manner by either graphic properties or synonymous words. Symbols are grouped by graphical similarities. Entries include a definition for each distinct use of the symbol with links to related images.
The word index is a straightforward search for a symbol that has a particular meaning but I find using the Graphic search the most interesting way to browse this site. You make a choice based on what the symbol looks like. When you search you are presented with an overview of a group of symbols with common graphic characteristics. There are 54 groups in all. From there you can browse the images. In a few minutes of browsing I discovered symbols from alchemy, the bronze age, ancient Egypt, runes, graffiti signs, gypsy signs, and Hopi Indian symbols.
Human cultures have produced a vast number of symbols so take some time out and have a good dig if you are interested in this area.