I have set up tableSuggestAjax as per every example I have seen anywhere. (code below)
One problem I am having is that even though all examples say the "suggestedItemsMethod" is expecting a String parameter, if I have any parameters in the actual method signature I get an EL exception. I had the same problem with inputSuggestAjax.

<s:tableSuggestAjax var="refData" id="incomeExpenseSuggest" startRequest="2"
 nextPageFieldClass="ajaxNextTablePageField"
 value="#{applicantOperationDetailsBackingBean.foo}" betweenKeyUp="300"
 columnOutClass="tableSuggestOut" columnHoverClass="tableSuggestHover"
 suggestedItemsMethod="#{applicantOperationDetailsBackingBean.suggestIncomeExpenseDescriptions}"
 tableStyleClass="ajaxTable" charset="utf-8">
 <t:column>
 <f:facet name="header">
 <s:outputText value="Income Type"/>
 </f:facet>
 <s:outputText for="incomeExpenseSuggest" label="#{refData.englishName}"/>
 </t:column>
 <t:column>
 <f:facet name="header">
 <s:outputText value="Code"/>
 </f:facet>
 <s:outputText for="code" label="#{refData.typeCode}"/>
 </t:column>

 </s:tableSuggestAjax>

public List getSuggestIncomeExpenseDescriptions(String value) {
 List<ReferenceData > result = new ArrayList<ReferenceData>();

 if (this.incomeAndExpenseRefData == null) {
 // initialize once
 this.incomeAndExpenseRefData = getRefDataService()
 .getReferenceDataList(RefDataTypes.INCOME_EXPENSE_TYPE);
 }

 for (Iterator iter = incomeAndExpenseRefData.iterator(); iter.hasNext();) {
 ReferenceData rd = (ReferenceData) iter.next();

 if ((value != null) &&
 rd.getEnglishName().toLowerCase().contains(value.toLowerCase())) {
 String data = rd.getEnglishName()+" ("+rd.getTypeCode()+")";
 result.add(data);

 }
 }

 return result;
 }